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 I sounded five short blasts to warn the vessel（）the immediate danger of collision.
单项选择题 I don’t think there is too much difference between transiting Suez Canal and panama Canal（）the tonnage certificate required.
单项选择题 Tell me（）, please.
