单项选择题
A.bearing pressure in a four-stroke\cycle acting single diesel engine is continually reversed
B.bearing pressure in a two-stroke\cycle single acting diesel engine is continually reversed
C.the maximum bearing pressure is higher in a single acting two-stroke/cycle diesel engine
D.two-stoke/cycle diesel engines require more complicated lubrication piping
单项选择题 Which of the fuel injection systems listed uses a spring loaded differential spray needle valve and individual pump for each cylinder?（）
单项选择题 The mode of control employed by an alarm circuit is a （）
单项选择题 The meat box temperature control circuit, as used in ship service refrigeration system, is an example of （）