单项选择题
The fog is lifted，so（）the radar．
A.close B.open C.switch off D.switch on
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（）.
单项选择题 The disadvantage of using a heaving line to pass a towline is that（）.
