单选题You are underway in fog and you hear one prolonged blast followed by two short blasts.This is a vessel（）.A TowingB Engaged on pilotage dutyC Aground in a fairwayD Stopped and making no way through the water

Approaching a anchorage in fog, you hear one short, one prolonged, and one short blast in that sequence on a ship’s whistle. This indicates ______.

A.A vessel towed

B.A vessel not under command and unable to maneuver.

C.A vessel anchored giving warning of her position.

D.A vessel stopped dead in the water.

If you hear more than six short blasts and one long blast of the whistle supplemented by the same signal on the general alarm, you should ______.

A.start the fire pump

B.go to your man overboard station

C.go to your lifeboat station

D.stand by for collision

You are on international waters during a heavy rainstorm and hear a vessel sounding a fog signal of one prolonged blast followed by two short blasts． Which of the following could it be？Ⅰ．A vessel laying submarine cable making way．Ⅱ．A pilot vessel on station at anchor．

A.Ⅰ only

B.Ⅱ only

C.Either Ⅰ or Ⅱ

D.Neither Ⅰ nor Ⅱ

If you do NOT understand the course or intention of an approaching vessel you should sound ___________.

A.one short blast

B.one prolonged blast

C.not less than five short blasts

D.not less than five prolonged blasts

On the high seas，a fog signal consisting of one prolonged blast followed by four short blasts would indicate the presence of a ______.

A.vessel being towed

B.fishing vessel engaged in trawling

C.vessel at anchor warning you of her location

D.power-driven pilot vessel on station underway