单项选择题
The bottom of the mast rests on a part of the keel called the mast（）.
A.foot B.heel C.step D.sole
单项选择题 The boom stops are installed on an offshore crane to（）.
单项选择题 The annual survey for endorsement of a Load Line Certificate must be held within（）.
单项选择题 The angle between the flukes and the shank of an anchor is called the（）.
