单项选择题
When the derrick is topped, the guy must be （）(放松).
A. slacked off B. sent away C. sent out D. taken in
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.
单项选择题 The sailor should （）(报告)it to the duty officer.
