单项选择题
Leg penetration to depths which require pullout forces greater than that which can be supplied by the buoyancy of the hull may exist in（）.
A.soft mud B.sand C.silt D.soft to firm clays
单项选择题 It is sometimes necessary to moor bow and stern to two mooring buoys in order to（）.
单项选择题 Installing tandem anchors on the same mooring line is referred to as（）.
单项选择题 In a crossing situation，a vessel fishing must keep out of the way of a vessel which is（）.
