单项选择题
What effect is achieved from soaking an anchor（）．
A.It allows the bottom soil to consolidate B.It gives the palms time to trip the anchor C.It stabilizes the mooring system D.It lubricates the anchor for better tripping
单项选择题 The centre of lateral resistance is（）.
单项选择题 That（）is not caused by shallow water.
单项选择题 Sometimes lights are（）by fog，haze，dust，smoke，or precipitation which may be present at the light，or between the light and the observer，and which is possibly unknown by the observer.
