Full-Length Mock Test 1 — RRB JE CBT 2 Technical Abilities Pattern (100 MCQs)

Instructions: This paper simulates the Technical Abilities-heavy portion of RRB JE CBT 2 for Civil Engineering, with additional questions from General Awareness, Computer Applications, and Environmental Engineering. Suggested time: 90 minutes.

Section A: Building Materials and Construction (20 Questions)

1. Ordinary Portland Cement (OPC) is manufactured chiefly from limestone and:
   (a) Clay (b) Steel scrap (c) Rubber (d) Glass
2. The compound in cement primarily responsible for early strength gain is:
   (a) Tricalcium silicate (C3S) (b) Dicalcium silicate (C2S) (c) Tetracalcium aluminoferrite (C4AF) (d) Gypsum
3. Gypsum is added during cement manufacture primarily to:
   (a) Retard/control the setting time (b) Increase colour brightness (c) Reduce cost with no functional purpose (d) Increase fineness alone
4. Fine aggregate is generally defined as aggregate passing through a:
   (a) 4.75 mm IS sieve (b) 40 mm IS sieve (c) 100 mm IS sieve (d) 1 mm IS sieve exclusively with nothing coarser ever classified as fine
5. Bulking of sand refers to the phenomenon where:
   (a) Moist sand occupies more volume than dry sand for the same mass (b) Dry sand occupies more volume than moist sand (c) Sand volume is unaffected by moisture (d) Sand converts to gravel upon wetting
6. The standard modular brick size as per IS 1077 is approximately:
   (a) 190×90×90 mm (b) 300×150×150 mm (c) 100×50×50 mm (d) 500×250×250 mm
7. Teak and sal timber are classified as:
   (a) Hardwood (b) Softwood (c) Plywood (d) Particle board exclusively
8. The frog of a brick primarily serves to:
   (a) Reduce weight and provide a key for mortar (b) Increase weight for stability (c) Serve purely decorative purposes with no functional role (d) Improve fire resistance exclusively
9. Fly ash, a common cement-replacement material, is a by-product of:
   (a) Coal-based thermal power generation (b) Steel smelting exclusively (c) Cement kiln operation itself with no external source (d) Timber processing
10. The specific gravity of ordinary Portland cement is approximately:
    (a) 3.15 (b) 1.0 (c) 7.85 (d) 0.5
11. English bond and Flemish bond refer to types of:
    (a) Brick masonry bonding patterns (b) Concrete mix designs (c) Steel reinforcement detailing (d) Timber jointing methods exclusively
12. A damp-proof course (DPC) is primarily provided to:
    (a) Prevent rising dampness from the foundation into walls (b) Increase compressive strength of masonry (c) Improve fire resistance exclusively (d) Reduce the building's weight
13. Plywood is manufactured by bonding together:
    (a) Thin layers (veneers) of wood with adhesive (b) Crushed stone and cement (c) Steel sheets (d) Glass fibres exclusively
14. The initial setting time of OPC, as per IS 269, should not be less than:
    (a) 30 minutes (b) 5 minutes (c) 300 minutes (d) 600 minutes
15. Coarse aggregate is generally defined as aggregate retained on a:
    (a) 4.75 mm IS sieve (b) 150 micron sieve (c) 1 mm sieve (d) 0.075 mm sieve
16. The process of removing excess water from the surface of freshly compacted concrete is called:
    (a) Bleeding (b) Curing (c) Segregation (d) Bulking
17. Segregation in concrete refers to:
    (a) Separation of coarse aggregate from the mortar matrix (b) Uniform distribution of all ingredients (c) The curing process (d) The setting-time test
18. Timber seasoning is primarily done to:
    (a) Reduce moisture content and improve durability/strength (b) Increase moisture content deliberately (c) Add colour (d) Increase weight for structural stability
19. A stretcher bond in brickwork uses bricks laid:
    (a) Lengthwise, with only stretcher faces visible (b) Only end-on, showing header faces exclusively (c) Diagonally with no defined pattern (d) Vertically on edge exclusively
20. The primary raw materials for brick manufacture are:
    (a) Suitable clay/soil (b) Steel and cement exclusively (c) Only sand with no clay (d) Only lime with no clay

Section B: Surveying (20 Questions)

21. Chain surveying is most suitable for areas that are:
    (a) Relatively small, open, and fairly flat (b) Highly congested urban areas with many obstructions (c) Mountainous terrain exclusively (d) Underwater sites exclusively
22. A Gunter's chain has a standard length of:
    (a) 66 feet (approximately 20.12 m) (b) 100 m (c) 30 feet (d) 500 m
23. The angle between the true meridian and magnetic meridian at a place is called:
    (a) Magnetic declination (b) Whole circle bearing (c) Reduced bearing (d) Local attraction
24. In levelling, a backsight refers to:
    (a) The first staff reading taken from an instrument station, typically on a point of known elevation (b) The last staff reading taken before moving the instrument (c) A horizontal angle reading (d) A type of bench mark
25. A benchmark (BM) is a point of:
    (a) Known/established elevation used as a reference (b) Unknown elevation requiring calculation each time (c) Purely decorative significance with no surveying use (d) Only horizontal position with no elevation relevance
26. A theodolite is primarily used to measure:
    (a) Horizontal and vertical angles (b) Only linear distances (c) Only soil moisture (d) Only concrete strength
27. Whole Circle Bearing (WCB) is measured from:
    (a) 0° to 360° clockwise from the north (b) 0° to 90° only (c) 0° to 180° only, counterclockwise (d) A fixed arbitrary reference with no defined range
28. Local attraction in compass surveying refers to disturbance of the magnetic needle caused by:
    (a) Nearby magnetic materials such as iron objects (b) Excessive sunlight (c) Rainfall (d) Air temperature changes exclusively
29. A dumpy level is primarily used for:
    (a) Determining differences in elevation between points (b) Measuring horizontal angles precisely (c) Measuring soil permeability (d) Testing concrete strength
30. Contour lines on a map represent:
    (a) Points of equal elevation (b) Points of equal soil type (c) Property boundaries exclusively (d) Roads exclusively
31. The closing error in a traverse survey arises due to:
    (a) Accumulated small errors in angle/distance measurement (b) Correct measurements with no error possible (c) Only instrument colour (d) Only weather with no measurement-related cause
32. A prismatic compass measures bearings with reference to:
    (a) Magnetic north (b) True north exclusively with no magnetic reference (c) A fixed building (d) The sun's position exclusively
33. Tacheometry is a surveying method used to determine distances:
    (a) Indirectly, using optical/stadia principles rather than direct taping (b) Only by direct chain measurement (c) Only via satellite signals (d) Only by pacing
34. The line of collimation in a levelling instrument refers to the:
    (a) Line joining the optical centre of the object glass and the intersection of cross-hairs (b) Line joining two bench marks (c) A property boundary line (d) A magnetic bearing line
35. Reciprocal levelling is used to eliminate errors due to:
    (a) Curvature of the earth and atmospheric refraction (b) Only instrument colour (c) Only operator height (d) Only weather with no other cause
36. A traverse survey consists of a series of connected:
    (a) Survey lines whose lengths and directions are measured (b) Unconnected random points with no measurement (c) Contour lines only (d) Only vertical measurements with no horizontal component
37. The fore bearing and back bearing of a line differ by:
    (a) 180 degrees (b) 90 degrees (c) 360 degrees (d) 45 degrees
38. An auto (automatic) level maintains a horizontal line of sight using a:
    (a) Compensator (b) Manual bubble adjustment for every reading (c) Magnetic needle (d) Barometric sensor
39. A total station integrates angle measurement with:
    (a) Electronic Distance Measurement (EDM) (b) A magnetic compass only (c) A dumpy level only (d) A chain and tape only
40. GPS position fixing in three dimensions typically requires signals from at least:
    (a) Four satellites (b) One satellite (c) Two satellites (d) Twenty satellites

Section C: Concrete Technology, RCC, and Theory of Structures (20 Questions)

41. In the concrete grade designation "M20," the number 20 refers to:
    (a) Characteristic compressive strength in N/mm² at 28 days (b) Cement content in kg per cubic metre (c) Curing period in days (d) Water-cement ratio multiplied by 20
42. The Slump Test is used to measure:
    (a) The workability of fresh concrete (b) The compressive strength of hardened concrete (c) The setting time of cement (d) The fineness of aggregate
43. The minimum recommended curing period for ordinary Portland cement concrete is generally cited as:
    (a) About 7 days (b) 1 hour (c) 1 day (d) 21 days as an absolute minimum with 7 days being insufficient under any condition
44. Clear cover to reinforcement in RCC members primarily protects steel from:
    (a) Corrosion and fire (b) Excessive strength gain (c) Workability loss (d) Changes in setting time
45. The water-cement ratio primarily affects concrete's:
    (a) Strength and durability (b) Colour exclusively (c) Aggregate size exclusively (d) Cement's chemical composition
46. A higher water-cement ratio, beyond the optimum, generally leads to:
    (a) Reduced concrete strength (b) Increased concrete strength without limit (c) No effect on strength (d) Immediate setting with no workability
47. The characteristic strength of concrete is defined statistically as the strength below which not more than what percentage of test results are expected to fall?
    (a) 5 percent (b) 50 percent (c) 95 percent (d) 100 percent
48. Reinforcement steel is primarily provided in RCC members to resist:
    (a) Tensile stresses, which plain concrete resists poorly (b) Compressive stresses exclusively, which concrete cannot resist at all (c) No particular stress; it is purely decorative (d) Only shear with no role in bending
49. A simply supported beam under a central point load experiences maximum bending moment at:
    (a) Mid-span (b) The supports (c) Nowhere along its length (d) Only at the ends equally with mid-span having zero moment
50. Shear force in a simply supported beam under a uniformly distributed load is typically maximum at:
    (a) The supports (b) Mid-span (c) Nowhere along the span (d) Only outside the beam's length
51. The neutral axis of a beam in bending is the axis where:
    (a) Bending stress is zero (b) Bending stress is maximum (c) Shear stress is always zero (d) Deflection is always maximum
52. Young's Modulus of Elasticity relates:
    (a) Stress and strain within the elastic limit (b) Only stress with no relation to strain (c) Only geometry with no material property (d) Only temperature and pressure
53. A truss is designed to carry loads primarily through members experiencing:
    (a) Axial tension or compression (b) Bending moments exclusively (c) Torsion exclusively (d) No internal force at all
54. The degree of static indeterminacy of a structure relates to:
    (a) The number of unknown reactions/forces exceeding available equilibrium equations (b) The colour of the structure (c) Only the material used (d) Only the structure's age
55. Poisson's ratio relates:
    (a) Lateral strain to longitudinal strain (b) Stress to time (c) Only temperature to strain (d) Only load to deflection with no strain concept
56. Compaction of concrete is primarily done to:
    (a) Remove entrapped air and achieve density (b) Increase air content deliberately (c) Reduce cement content (d) Increase setting time
57. A cantilever beam is supported at:
    (a) One end only, being fixed, with the other end free (b) Both ends, being simply supported (c) Multiple intermediate points with no end support (d) No point at all
58. The modulus of rupture of concrete relates to its:
    (a) Flexural (bending) tensile strength (b) Compressive strength directly with no distinction (c) Workability (d) Setting time
59. Prestressed concrete primarily improves performance by:
    (a) Inducing compressive stress before service loads are applied, counteracting tensile stresses (b) Removing all reinforcement entirely (c) Eliminating the need for curing (d) Increasing water content deliberately
60. Creep in concrete refers to:
    (a) Gradual, time-dependent deformation under sustained load (b) Instantaneous elastic deformation only (c) A type of concrete additive (d) A curing method

Section D: Geotechnical, Hydraulics, and Environmental Engineering (20 Questions)

61. Soil particles larger than 4.75 mm, as per the Indian Standard Soil Classification System, are classified as:
    (a) Gravel (b) Sand (c) Silt (d) Clay
62. The Plasticity Index (PI) of a soil is calculated as:
    (a) Liquid Limit minus Plastic Limit (b) Liquid Limit plus Plastic Limit (c) Liquid Limit divided by Plastic Limit (d) Liquid Limit multiplied by Plastic Limit
63. Darcy's Law for flow through soil is generally expressed as:
    (a) v = k·i (velocity proportional to hydraulic gradient) (b) v = k/i (c) v = k + i (d) v = k − i
64. The Standard Proctor Test determines the relationship between dry density and:
    (a) Moisture content (b) Shear strength directly (c) Permeability directly (d) Bearing capacity directly
65. Terzaghi's bearing capacity theory is used to estimate:
    (a) The bearing capacity of soil beneath foundations (b) The permeability of soil (c) The plasticity index (d) The optimum moisture content directly
66. The standard density of water, commonly used in engineering calculations, is approximately:
    (a) 1000 kg/m³ (b) 100 kg/m³ (c) 500 kg/m³ (d) 2000 kg/m³
67. Bernoulli's Theorem states that, along a streamline (ignoring losses), the sum of pressure head, velocity head, and elevation head is:
    (a) Constant (b) Always zero (c) Always increasing (d) Dependent solely on pipe material with no energy basis
68. Laminar pipe flow is generally associated with Reynolds Numbers:
    (a) Below approximately 2000 (b) Above approximately 4000 (c) Exactly 3000 always (d) Above 10,000 always
69. A Venturimeter measures flow rate based on:
    (a) A pressure difference created by a constriction (Bernoulli's principle) (b) Magnetic field changes (c) Sound reflection (d) Direct weighing of fluid
70. Among common irrigation methods, which is generally considered most water-efficient?
    (a) Drip irrigation (b) Flood irrigation (c) Border irrigation (d) Furrow irrigation, being more efficient than drip in all cases
71. A barrage, compared to a plain weir, allows:
    (a) More controlled water regulation via gates (b) Less control over flow (c) No diversion of water at all (d) Groundwater recharge exclusively with no surface function
72. The primary purpose of a canal lining is to:
    (a) Reduce seepage losses (b) Increase seepage deliberately (c) Increase evaporation (d) Reduce flow velocity to zero
73. BOD (Biochemical Oxygen Demand) is a measure of:
    (a) The oxygen required by microorganisms to decompose organic matter in water (b) The total dissolved solids in water (c) The pH of water (d) The turbidity of water exclusively with no biological basis
74. The standard BOD test is conducted over an incubation period of:
    (a) 5 days at 20°C (commonly cited as BOD5) (b) 5 minutes (c) 28 days (d) 1 hour
75. A septic tank is primarily used for:
    (a) On-site treatment/settlement of sewage in areas without a sewer network (b) Storing drinking water exclusively (c) Generating electricity (d) Testing soil bearing capacity
76. Chlorination of water supply is primarily done to:
    (a) Disinfect water by killing pathogenic organisms (b) Increase turbidity deliberately (c) Reduce dissolved oxygen (d) Add colour to water
77. The pH of pure, neutral water is approximately:
    (a) 7 (b) 0 (c) 14 (d) 3
78. A weir, as a hydraulic structure, is primarily used to:
    (a) Measure or regulate flow by raising the upstream water level (b) Store groundwater exclusively (c) Purify sewage (d) Measure soil permeability
79. Sedimentation, as a water/wastewater treatment step, primarily removes:
    (a) Suspended solids by gravity settling (b) Dissolved gases exclusively (c) Pathogens exclusively with no solids removal (d) Colour exclusively with no solids removal
80. Coagulation-flocculation in water treatment primarily helps to:
    (a) Aggregate fine suspended particles for easier removal (b) Disinfect water chemically with no physical effect (c) Increase turbidity deliberately (d) Remove dissolved salts exclusively

Section E: General Awareness, Computer Applications, and Current Affairs (20 Questions)

81. RRB stands for:
    (a) Railway Recruitment Board (b) Regional Rural Bank (c) Road Repair Board (d) Rural Railway Bureau
82. The CBT in RRB JE examinations stands for:
    (a) Computer Based Test (b) Central Board Test (c) Combined Basic Training (d) Civil Bridge Test
83. A computer's Central Processing Unit (CPU) is often called the:
    (a) "Brain" of the computer (b) Only the storage device (c) Only the display device (d) Only the input device
84. RAM (Random Access Memory) is a type of:
    (a) Volatile memory that loses data when power is off (b) Permanent, non-volatile storage (c) An input device exclusively (d) An output device exclusively
85. The primary function of an operating system is to:
    (a) Manage computer hardware and software resources (b) Only display graphics with no resource management (c) Only connect to the internet (d) Only print documents
86. MS Excel is primarily used for:
    (a) Spreadsheet calculations and data organisation (b) Only word processing (c) Only image editing (d) Only video editing
87. India's Ministry of Railways oversees the operation of Indian Railways, one of the world's:
    (a) Largest railway networks (b) Smallest railway networks (c) Only privately owned networks (d) Only freight-only networks with no passenger service
88. The Indian Railways' zonal system divides operations into multiple:
    (a) Railway zones for administrative/operational purposes (b) A single undivided national zone (c) Only two zones nationwide (d) Zones based solely on train colour
89. Bharat Ratna, India's highest civilian award, has been conferred on individuals in fields including:
    (a) Science, arts, public service, and literature, among others (b) Only sports (c) Only military service (d) Only politics
90. The Reserve Bank of India (RBI) primarily functions as India's:
    (a) Central bank (b) Largest commercial bank exclusively (c) Stock exchange (d) Income tax department
91. The Indian Constitution came into effect on:
    (a) 26 January 1950 (b) 15 August 1947 (c) 26 November 1949 (d) 2 October 1950
92. The Prime Minister of India is the head of the:
    (a) Executive branch of government (b) Judiciary exclusively (c) Legislature exclusively with no executive role (d) Election Commission
93. A firewall in computer networking is primarily used to:
    (a) Protect a network from unauthorised access (b) Increase internet speed exclusively (c) Store data permanently (d) Print documents
94. The full form of "PDF" is:
    (a) Portable Document Format (b) Personal Data File (c) Printed Document Form (d) Public Data Format
95. Indian Railways is administratively headed at the national level by the:
    (a) Railway Board (b) State governments individually (c) A private corporation (d) The judiciary
96. The metric unit of force in the SI system is the:
    (a) Newton (b) Joule (c) Watt (d) Pascal
97. The SI unit of pressure/stress is the:
    (a) Pascal (b) Newton (c) Joule (d) Watt
98. India's national river-linking and irrigation infrastructure discussions commonly reference projects such as the:
    (a) Ken-Betwa link (b) Only foreign river projects with no domestic example (c) Only maritime port projects (d) Only urban metro projects
99. A spreadsheet cell reference like "B5" refers to:
    (a) Column B, Row 5 (b) Row B, Column 5 (c) A fixed constant with no positional meaning (d) A formula name exclusively
100. Continuous professional updating of technical knowledge (IS code revisions, new construction technologies) is important for a Junior Engineer primarily because:
     (a) Engineering standards and practices evolve over time (b) Standards never change once set (c) Only theoretical knowledge matters with no practical updating needed (d) Updating knowledge has no bearing on job performance

Answer Key with Explanations

Section A: 1.(a) OPC is made chiefly from limestone and clay. 2.(a) C3S drives early strength gain. 3.(a) Gypsum retards/controls setting time. 4.(a) Fine aggregate passes the 4.75 mm sieve. 5.(a) Bulking means moist sand occupies more volume than dry sand of the same mass. 6.(a) IS 1077 modular brick size is about 190×90×90 mm. 7.(a) Teak and sal are hardwoods. 8.(a) The frog reduces weight and keys mortar. 9.(a) Fly ash is a thermal-power-plant by-product. 10.(a) OPC's specific gravity is about 3.15. 11.(a) English and Flemish bonds are brick masonry bonding patterns. 12.(a) DPC prevents rising dampness into walls. 13.(a) Plywood bonds thin wood veneers with adhesive. 14.(a) OPC's initial setting time should not be less than 30 minutes. 15.(a) Coarse aggregate is retained on the 4.75 mm sieve. 16.(a) Bleeding is surface water rising from freshly compacted concrete. 17.(a) Segregation separates coarse aggregate from the mortar matrix. 18.(a) Seasoning reduces moisture and improves timber durability/strength. 19.(a) Stretcher bond shows only stretcher (lengthwise) faces. 20.(a) Suitable clay/soil is the primary brick raw material.

Section B: 21.(a) Chain surveying suits small, open, fairly flat areas. 22.(a) A Gunter's chain is 66 feet (~20.12 m). 23.(a) The true-magnetic meridian angle is magnetic declination. 24.(a) A backsight is the first reading, typically on a known-elevation point. 25.(a) A benchmark has known/established elevation. 26.(a) A theodolite measures horizontal and vertical angles. 27.(a) WCB is measured 0°-360° clockwise from north. 28.(a) Local attraction arises from nearby magnetic materials. 29.(a) A dumpy level determines elevation differences. 30.(a) Contour lines represent equal elevation. 31.(a) Closing error arises from accumulated small measurement errors. 32.(a) A prismatic compass references magnetic north. 33.(a) Tacheometry determines distances indirectly via optical/stadia methods. 34.(a) The line of collimation joins the object glass's optical centre and cross-hair intersection. 35.(a) Reciprocal levelling eliminates curvature/refraction errors. 36.(a) A traverse is a series of connected, measured survey lines. 37.(a) Fore and back bearings differ by 180 degrees. 38.(a) An auto level uses a compensator. 39.(a) A total station integrates angle measurement with EDM. 40.(a) 3D GPS fixing needs at least four satellites.

Section C: 41.(a) "M20" denotes 20 N/mm² characteristic compressive strength at 28 days. 42.(a) The Slump Test measures workability. 43.(a) About 7 days is generally cited as a minimum curing period. 44.(a) Clear cover protects steel from corrosion and fire. 45.(a) Water-cement ratio primarily affects strength/durability. 46.(a) Excess water-cement ratio reduces strength. 47.(a) Characteristic strength allows at most 5 percent of results to fall below it. 48.(a) Reinforcement resists tensile stresses concrete handles poorly. 49.(a) Maximum bending moment under a central point load occurs at mid-span. 50.(a) Maximum shear under UDL occurs at the supports. 51.(a) The neutral axis has zero bending stress. 52.(a) Young's Modulus relates stress and strain elastically. 53.(a) Truss members carry axial tension/compression. 54.(a) Static indeterminacy relates unknowns exceeding equilibrium equations. 55.(a) Poisson's ratio relates lateral to longitudinal strain. 56.(a) Compaction removes entrapped air, achieving density. 57.(a) A cantilever is fixed at one end, free at the other. 58.(a) Modulus of rupture is flexural tensile strength. 59.(a) Prestressing induces counteracting compressive stress before service loads. 60.(a) Creep is time-dependent deformation under sustained load.

Section D: 61.(a) Particles above 4.75 mm are gravel per ISSCS. 62.(a) PI = Liquid Limit − Plastic Limit. 63.(a) Darcy's Law: v = k·i. 64.(a) The Proctor Test relates dry density to moisture content. 65.(a) Terzaghi's theory estimates foundation bearing capacity. 66.(a) Water's standard density is about 1000 kg/m³. 67.(a) Bernoulli's Theorem: total head is constant along a streamline. 68.(a) Laminar flow generally occurs below Reynolds Number ~2000. 69.(a) A Venturimeter uses a constriction-based pressure difference. 70.(a) Drip irrigation is generally the most water-efficient method. 71.(a) A barrage allows more controlled regulation via gates. 72.(a) Canal lining reduces seepage losses. 73.(a) BOD measures oxygen needed to decompose organic matter. 74.(a) Standard BOD testing uses 5 days at 20°C. 75.(a) A septic tank provides on-site sewage treatment/settlement. 76.(a) Chlorination disinfects water by killing pathogens. 77.(a) Pure neutral water has a pH of about 7. 78.(a) A weir measures/regulates flow by raising upstream water level. 79.(a) Sedimentation removes suspended solids by gravity settling. 80.(a) Coagulation-flocculation aggregates fine particles for removal.

Section E: 81.(a) RRB stands for Railway Recruitment Board. 82.(a) CBT stands for Computer Based Test. 83.(a) The CPU is often called the computer's "brain." 84.(a) RAM is volatile memory. 85.(a) An OS manages hardware/software resources. 86.(a) MS Excel is used for spreadsheets/data organisation. 87.(a) Indian Railways is among the world's largest railway networks. 88.(a) Indian Railways is divided into zones for administration. 89.(a) Bharat Ratna spans science, arts, public service, literature, and more. 90.(a) The RBI is India's central bank. 91.(a) The Constitution came into effect 26 January 1950. 92.(a) The PM heads the executive branch. 93.(a) A firewall protects a network from unauthorised access. 94.(a) PDF stands for Portable Document Format. 95.(a) The Railway Board heads Indian Railways nationally. 96.(a) The SI unit of force is the Newton. 97.(a) The SI unit of pressure/stress is the Pascal. 98.(a) The Ken-Betwa link is a commonly referenced Indian river-linking project. 99.(a) "B5" means Column B, Row 5. 100.(a) Engineering standards/practices evolve, requiring continuous updating.