单项选择题
A backlash below a lock is defined as a（）.
A.current setting your vessel on the wall B.current setting into the lock chamber C.an eddy working along the lower guide wall D.current setting counterclockwise
单项选择题 A “spring line” is（）.
单项选择题 A “sheepshank” is used to（）.
单项选择题 A “reaching” course is one in which the wind（）.
