单项选择题
A.must B.ought to C.have to D.never
Routine radio communications should be no more than（）.A...
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
PORT A BIT SLUGGISH means that port rudder（）.A.answers ...
单项选择题PORT A BIT SLUGGISH means that port rudder（）.
A.answers very well B.rudder answers all right C.answers slow D.answers fast
Free communication effect is in direct proportion to（）....
单项选择题Free communication effect is in direct proportion to（）.
A.length and width of space B.length of space only C.width of space only D.neither length nor width
