单项选择题
Shall we（）wait at the roadstead till there is a free berth for us?
A.must B.ought to C.have to D.never
单项选择题 Routine radio communications should be no more than（）.
单项选择题 PORT A BIT SLUGGISH means that port rudder（）.
单项选择题 Free communication effect is in direct proportion to（）.
