单项选择题
What is the first thing you would check on taking over a watch?（）
A.the bilges B.the periscope C.the water level D.the oil pressure
单项选择题 Soot blowers should be used in proper sequence so that（）
单项选择题 The valve that prevents water from backing out of the boiler into the feed line is the（）.
单项选择题 The mechanical exhaust valve operation system is replaced by（）in an electronic controlled ME engine.
