单项选择题
What is the best guide for determining the proper scope of anchor chain to use for anchoring in normal conditions（）.
A.One shot of chain for every ten feet of water B.One shot of chain for every fifteen feet of water C.One shot of chain for every thirty feet of water D.One shot of chain for every ninety feet of water
单项选择题 What effect is achieved from soaking an anchor（）．
单项选择题 The centre of lateral resistance is（）.
单项选择题 That（）is not caused by shallow water.
