单项选择题
A.thrust B.stern C.engine D.speed
Keep to the middle of the（）(航道) ！A.buoyB.markC.beaconD....
单项选择题Keep to the middle of the（）(航道) ！
A.buoy B.mark C.beacon D.channel
An officer is always（）（值班）on the bridge .A. on watchB. ...
单项选择题An officer is always（）（值班）on the bridge .
A. on watch B. taking watches C. standing watches D. keep watches
What（）(航速)?A.speedB.lineC.wakeD.route
单项选择题What（）(航速)?
A.speed B.line C.wake D.route
