单选题When the derrick is topped, the guy must be （）(放松).A slacked offB sent awayC sent outD taken in

The preventer guy，as used on a conventional yard and stay rig，______．

A.Is rigged at an angle of 70° to 90° from the guy it assists

B.Takes the strain imposed on the schooner guy when burtoning cargo

C.Is rigged when lifting cargo that exceeds the SWL of a single whip

D.Should take the strain if the regular guy parts

The connected joints of pipe，usually made of three joints of pipe approximately 90 feet long，racked in the derrick when making a trip are called a ______．

A.String

B.Stand

C.Joint

D.Standpipe

Navigation lights must be displayed in all weathers from sunset to sunrise. They also _____.

A.must be displayed when day signals are being used

B.must be displayed when moored to a pier

C.may be extingushed at night on open waters when no other vessels are in the area

D.may be displayed during daylight

When the inert gas pressure is being ______ in the cargo tanks，particular attention should be paid to obtaining an oxygen concentration．

A.topped up

B.braced

C.tommed down

D.shored

In a married falls rig at the after end of a hatch，a boom is rigged in a fore and aft line through its heel．Stresses on the outboard guy will be LEAST if the guy is made fast at a point ______．

A.Abreast the heel

B.At right angles to the boom when viewed from above

C.Aft of the heel

D.Forward of the spiderband