Oily rags stored in a pile that is open to the atmosphere are a hazard because they may（）.

单项选择题Normally，potable water systems are connected directly to the（）.

A.fire-main system
B.feed-water system
C.freshwater sanitary system
D.domestic water tank

单项选择题Line throwing apparatus aboard ship must contain（）.

A.two rockets，one of which shall be the buoyant type
B.three rockets，one of which shall be the buoyant type
C.four rockets，two of which shall be the buoyant type
D.five rockets，two of which shall be the buoyant type

单项选择题In order for the automatic lifeboat drain to operate properly（）.

A.the cap should be removed to drain the boat when it is waterborne
B.the cage must be free of rubbish or the ball may not seat properly
C.there is an automatic ball check located in a siphon tube
D.the small lever to release the rubber ball float must be turned counterclockwise

单项选择题In launching a covered lifeboat，what would safely lower the lifeboat from inside the lifeboat cabin?（）

A.Frapping line
B.Tricing line
C.Rottmer release
D.Winch remote control wire

单项选择题In addition to the life jackets stowed at each berth location，life jackets must be stowed at each watch station and（）.

A.the mess room
B.each lifeboat
C.each industrial work site
D.each fire station