Which one of the followings may not be checked before engine starting?（）

单项选择题The is employed to warm up a large diesel engine before its starting（）

A.hot air
B.hot boiler water
C.cylinder water
D.hot seawater

单项选择题In slow speed two-stroke engines,（）the fresh air entering begins when and stops as（）

A.the inlet port is opened by the up coming piston； the port is closed by the down going
B.the inlet valve is opened by the down going piston；the inlet valve is closed
C.the inlet port is opened by the down going piston；the port is closed by the up coming
D.the inlet valve is opened

单项选择题Usually we take the cooling effect of the air flown through the cylinder during the overlap period as（）

A.inevitable
B.harmful
C.helpful
D.unacceptable

单项选择题When the air charge contacts with the cylinders and pistons and mixes with the residual gases, it will（）

A.increase in temperature
B.lose its energy partly
C.expand and do work
D.begin to be compressed

单项选择题“This increase in charge air density is accomplished on most modern diesel engine types by use of exhaust gas turbo-charging, in which a turbine wheel driven by exhaust from the engine is rigidly coupled to a centrifugal type air compressor” According to this sentence, we can know that increases density（）, drives the compressor directly（）

A.a modern diesel engine；a turbine wheel
B.a modem diesel engine；exhaust gases
C.a compressor；an exhaust gas turbocharger
D.a compressor；a turbine wheel