单项选择题
The （）(重吊杆) can lift heavy cargo.
A. heavy cargo derrick B. heavy deck C. jumbo boom D. heavy block
单项选择题 The（）(千斤索) is a wire used to take the weight off.
单项选择题 The （）(双杆联吊) is that two booms are used with a single hook.
单项选择题 The （）(包装货) is loaded and unloaded by cargo sling.
