单项选择题
If the engine of a survival craft does not start，check to see（）.
A.that the fuel valve is open B.if the air supply system is open C.if the water sprinkler system is open D.if the limit switch is on
单项选择题 If a gasoline engine turns over freely but will not start，the cause is generally（）.
单项选择题 Each cylinder in a two stroke cycle engine experiences combustion（）.
单项选择题 Centrifugal pumps have what advantage(s) over reciprocating pumps?（）.
