单项选择题
Routine radio communications should be no more than（）.
A.one minute B.three minutes C.five minutes D.eight minutes
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（）.
单项选择题 Electrical wiring on all T-Boats must be（）.
