The crankcase cover should never be allowed to open for investigation when （）
举一反三
- They should never be allowed to abuse their authority and position.
- A cover letter should never _______ one page; often a far shorter letter will suffice.
- The old cover of the book ______. A: must be used B: is sometimes used C: should never be used
- If a crankcase explosion occurs in a diesel engine, you should stop the engine and（） A: immediately open all crankcase relief ports B: increase crankcase exhauster speed to draw cool air into the engine C: allow the engine to cool naturally D: increase crank case scavenge air to remove unburned gase
- You should open the doors when you use it.