单项选择题
A sling is a device used in（）.
A.hoisting cargo aboard a vessel B.hoisting personnel aboard a vessel C.securing a small boat to a large vessel D.hoisting the anchor
单项选择题 A large basin cut into the shore，closed off by a caisson，and used for drydocking of ships is known as a（）.
单项选择题 Which action will affect the trim of a vessel? （）
