单项选择题
Stop（）the derrick at once，the gooseneck is bent.
A.to use B.to operate C.maneuvering D.using
单项选择题 On no account（）to be exceeded.
单项选择题 On a ship crane，the load chart relates the allowable load to the combination of boom length and（）.
单项选择题 Oil product samples should be taken from the（）.
