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單項(xiàng)選擇題

The external flotation bladder on an immersion suit should be inflated（）.

A.before you enter the water
B.after you enter the water
C.after one hour in the water
D.after you notice that your suit is losing buoyancy

單項(xiàng)選擇題

The Experimental Lighthouse-buoy has no navigational significance and may be removed at will.The above sentence means（）.

A.It's of no use for navigation and would be removed with notice
B.It's useful in navigation and may be removed without notice
C.It's helpless in navigation and may be removed without notice
D.It's helpful in navigation and may be removed without notice