单选题Sailing vessels are stand-on over power-driven vessels except（）.A in a crossing situationB in a meeting situationC when they are the overtaking vesselD on the inland waters of the PR China

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

A vessel sailing shall keep out of the way of all of the following vessels except a vessel ______.

A.not under command

B.engaged on pilotage duty

C.restricted in her ability to maneuver

D.engaged in fishing

Radar reflectors are required for ______.

A.all fishing vessels over 39 feet in length

B.sail-propelled fishing vessels

C.all fishing vessels of less than 200 GT

D.wooden hull fishing vessels with a poor radar echo

In which situation do the Rules require both vessels to change course ?______.

A.Two power-driven vessels meeting head-on

B.Two power-driven vessels crossing when it is apparent to the stand-on vessel that the give-way vessel is not taking appropriate action

C.Two sailing vessels crossing with the wind on the same side

D.All of the above

There shall be two principal ______ through the harbor for the passage of vessels of over 60 tons burden．

A.straits

B.channels

C.canals

D.roadsteads

The following conditions，except ______，require that vessels be towed through the entire Canal．

A.vessels without mechanical motive power

B.vessels with disabled machinery or bad steering

C.vessels with dangerous cargoes on board

D.vessels liable to become unmanageable for any other reason

Sailing vessels are stand-on over power-driven vessels except ______.

A.in a crossing situation

B.in a meeting situation

C.when they are the overtaking vessel

D.on the inland waters of the PR China