单项选择题
When the derrick is stopped, the guy must be （）(收好).
A.taken in B.slacked off C.adjusted D.stowed
单项选择题 When the derrick is topped, the guy must be （）(放松).
单项选择题 A （）(重吊杆)is used for lifting long heavy cargo.
单项选择题 You should release the （）(重型螺栓)on top of the cover.
