单项选择题
A.it B.this C.that D.what
The burden of proving unseaworthiness is upon those who...
单项选择题The burden of proving unseaworthiness is upon those who（）it.
A.approves B.alleges C.allows D.permits
The bottom of the mast rests on a part of the keel call...
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
The boom stops are installed on an offshore crane to（）....
单项选择题The boom stops are installed on an offshore crane to（）.
A.prevent the boom from being raised too high B.prevent the boom from swinging C.support the boom when not in use D.prevent the boom from being lowered
