单项选择题
A.deeply-grooved drum on the windlass with sprockets which engage the links of the anchor chain
B.winch that is running out of control due to a failure of the overspeed trips
C.line that has jumped off the gypsyhead while under strain
D.nylon line that parts under strain and whips back in a hazardous manner
单项选择题 A single fitting installed in a pipeline that either blanks off the pipe or allows a full flow passage of a liquid through the pipe is referred to as a（）.
单项选择题 A set of interior steps on a ship leading up to a deck from below is known as（）.
单项选择题 A measurement device for inspecting anchor chain is the（）.