单项选择题
A.at the first stop after a long voyage egby anchoring if possible
B.at the first stop after arrival at harbor
C.at the first stop after low load running
D.at the first stop after passing river or canal passage
单项选择题 Always ensure that the turning gear is（）, even at the quay, the wake from other ships may turn the propeller and thus the engine.
单项选择题 In general, the oil mist defectors include a base plate with air blast pumpThe function of air blast pump is to （）crankcase.
单项选择题 In general, the oil mist detectors include a built-in heating unit and a compact plug for electrical connectionThe function of heating unit is to （）