单项选择题
The most common type of davit found on merchant vessels today is the（）.
A.radial B.sheath-screw C.gravity D.quadrantal
单项选择题 The holding capability of an anchor is primarily determined by the（）.
单项选择题 The function of the bypass valve on the self-contained breathing apparatus is to（）.
单项选择题 The extension of the after part of the keel in a single-screw vessel upon which the stern post rests is called the（）.
