单选题A signal of one prolonged，one short，one prolonged，and one short blast，in that order is given by a vessel（）.A engaged on pilotage dutyB in distressC at anchorD being overtaken in a narrow channel

A head on situation shall be deemed to exist at night when a power-driven vessel sees another power-driven vessel ahead and ______.

A.one sidelight and the masthead light are visible

B.the vessels will pass closer than half a mile

C.both vessels sound one prolonged blast

D.both sidelights and masthead light(s) are visible

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.

According to the NAS's report, one of the problems in end-of-life care is ______.

A) prolonged medical procedures

B) inadequate treatment of pain

C) systematic drug abuse

D) insufficient hospital care

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

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

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