单项选择题
The force exerted by a propeller which tends to throw the stern right or left is called（）.
A.slip B.sidewise force C.rotational force D.thrust
单项选择题 The fog is lifted，so（）the radar．
单项选择题 The external flotation bladder of an immersion suit should be inflated（）.
单项选择题 The dumping of refuse in a lock is permitted（）.
