Câu hỏi luyện tập mẫu

Một vài câu hỏi mẫu từ ngân hàng miễn phí này, kèm giải thích đầy đủ. Dùng công cụ luyện tập ở trên cho toàn bộ.

1. 1. Core Trades

   A concrete mix is batched with 620 pounds of cement per cubic yard. To hold the water-cement (w/c) ratio at a MAXIMUM of 0.45, what is the greatest amount of water that may be used per cubic yard?

   • a.About 279 pounds
   • b.About 344 pounds
   • c.About 248 pounds
   • d.About 310 pounds

   Đáp án: a

   Giải thích: The w/c ratio is water weight divided by cement weight, so maximum water = 0.45 x 620 = 279 lb. 248 lb corresponds to a 0.40 ratio, 310 lb to 0.50, and 344 lb to 0.55, all of which miss the specified 0.45 limit.

   Nguồn: 2025 CA Building Code (CBC) Chapter 19 (Concrete)

2. 2. Core Trades

   During hot-weather concreting at 95 degrees F with dry wind, the MOST important immediate practice to prevent surface defects is to:

   • a.Protect the surface from moisture loss with fogging, evaporation retarder, or prompt curing
   • b.Use a higher-slump mix and delay finishing so the crew has more time before the surface has to be closed up
   • c.Add extra retarder and leave it exposed so the set is pushed back until the wind drops later in the day
   • d.Increase the mix water to keep it workable so the crew can keep placing without the load stiffening in the truck

   Đáp án: a

   Giải thích: In hot, windy conditions rapid evaporation causes plastic shrinkage cracking, so the priority is reducing moisture loss with fogging, evaporation retarders, and prompt curing. Adding mix water raises the water-cement ratio and weakens the concrete; leaving it exposed worsens evaporation.

   Nguồn: 2025 CA Building Code, Chapter 19 (Concrete)

3. 3. Core Trades

   The MOST reliable method to prevent backflow contamination of the potable water supply at a fixture is:

   • a.Increasing the supply water pressure so flow always moves to the fixture
   • b.Installing a single check valve on the branch serving the fixture
   • c.Adding length to the supply pipe so contamination has farther to travel
   • d.Providing a physical air gap of adequate height above the fixture flood rim

   Đáp án: d

   Giải thích: A physical air gap (an unobstructed vertical space, typically at least twice the pipe diameter and not less than 1 inch, above the flood rim) cannot be defeated because there is no continuous path for backflow. Check valves are mechanical and can fail; higher pressure and longer pipe do nothing to stop back-siphonage.

   Nguồn: 2025 CA Plumbing Code §603.0

4. 4. Core Trades

   A trench measures 90 ft long, 3 ft wide, and 4 ft deep. How many bank (in-place) cubic yards of soil must be excavated?

   • a.120 cubic yards
   • b.40 cubic yards
   • c.30 cubic yards
   • d.20 cubic yards

   Đáp án: b

   Giải thích: Volume = 90 x 3 x 4 = 1,080 cubic feet; 1,080 / 27 = 40 cubic yards. The 20 and 30 answers understate the cross-section, and 120 leaves the result in cubic feet without dividing by 27.

5. 5. Finish Trades

   Under CALGreen, composite wood used in interior casework, such as particleboard cabinet boxes, must meet formaldehyde emission limits. This requirement is set MAINLY to:

   • a.Lower the cost of the cabinets
   • b.Make the cabinets waterproof
   • c.Protect indoor air quality and occupant health
   • d.Increase the strength of the cabinets so particleboard boxes can carry heavier countertops

   Đáp án: c

   Giải thích: CALGreen caps formaldehyde emissions from composite wood products (matching CARB standards) to protect indoor air quality and occupant health. The limits are about emissions, not structural strength, cost, or water resistance.

   Nguồn: 2025 CALGreen §4.504

6. 6. Framing & Structural

   A weep screed at the base of a stucco wall must be located at least how far above adjacent surfaces?

   • a.At least 4 inches above earth or 2 inches above paved areas
   • b.Flush with the finished grade, meeting the soil directly
   • c.At least 8 inches above paved areas in every case
   • d.At least 12 inches above earth at every wall base

   Đáp án: a

   Giải thích: The foundation weep screed must sit a minimum of 4 inches above earth or 2 inches above paved surfaces so moisture in the stucco can drain out above the splash and grade line. Twelve inches, flush with grade, and 8 inches above paving are not the code-required minimums.

   Nguồn: 2025 CA Residential Code §R703.7.2.1

7. 7. Finish Trades

   When applying an oil-based stain and clear topcoat to interior wood trim, why should oily rags be spread out or placed in a sealed metal container after use?

   • a.To speed the drying of the topcoat by letting air reach the finish still held in the cloth
   • b.To keep them clean for reuse on the next coat instead of buying new rags for the rest of the job
   • c.Because they can spontaneously combust as the oil oxidizes and generates heat
   • d.To prevent the stain color from fading in the rags so later touch-ups still match the trim

   Đáp án: c

   Giải thích: Rags soaked with oil-based finishes can self-heat as the oil oxidizes and may spontaneously ignite if bunched up, so they must be spread flat to cool or sealed in a listed metal container with water. Reuse, color fading, and topcoat drying are not the safety reason for this practice.

8. 8. Planning & Estimating

   A roof has 1,800 square feet of surface. Adding 10 percent for waste, how many roofing squares should be ordered (1 square = 100 sq ft)?

   • a.20 squares
   • b.22 squares
   • c.19 squares
   • d.18 squares

   Đáp án: a

   Giải thích: One roofing square covers 100 sq ft. Base area = 1,800 / 100 = 18 squares. Add 10 percent waste: 18 x 1.10 = 19.8 squares. Since material is sold in whole squares and you cannot under-order, round up to 20 squares. Option d ignores waste. Option c rounds 19.8 down, leaving a shortage. Always round material orders up.

9. 9. Safety

   A straight (non-self-supporting) ladder is set up against a wall. What placement BEST follows the recommended angle for safe use?

   • a.Any angle is fine if the top is tied off
   • b.Base 1 foot out for every 4 feet of working height
   • c.Base 4 feet out for every 1 foot of working height
   • d.Base directly against the wall, nearly vertical

   Đáp án: b

   Giải thích: The safe setup is roughly a 4-to-1 ratio: the base should be about 1 foot away from the wall for every 4 feet of working height. Option c reverses the ratio, making the ladder dangerously flat. Option d is nearly vertical and prone to tipping backward. Option a ignores the angle even though tying off is also good practice. The 4-to-1 rule keeps the ladder stable against sliding and tipping.

   Nguồn: Cal/OSHA Title 8 §1675

10. 10. Planning & Estimating

    Match each work item to its CSI MasterFormat division: (i) built-up roofing and wall insulation, (ii) interior painting and ceramic tile, (iii) exterior aluminum windows.

    • a.(i) 08, (ii) 07, (iii) 09
    • b.(i) 07, (ii) 09, (iii) 08
    • c.(i) 09, (ii) 07, (iii) 05
    • d.(i) 05, (ii) 08, (iii) 07

    Đáp án: b

    Giải thích: Correct: roofing, waterproofing, and insulation are Division 07 (Thermal & Moisture Protection); painting and tile are Division 09 (Finishes); windows and doors are Division 08 (Openings). The other options scramble these assignments.