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（）.

A ship crane which has been idle for a period of over s...

单项选择题A ship crane which has been idle for a period of over six months shall be inspected to the same standards as a（）.

A sheepshank is used to（）.A.keep a line from frayingB.j...

单项选择题A sheepshank is used to（）.

A sextant having an index error that is off the arc has...

单项选择题A sextant having an index error that is off the arc has a（）.