单项选择题
A. heavy derrick B. pulley block C. topping lift block D. guy tackle
The （）(重吊杆) can lift heavy cargo.A. heavy cargo derrick...
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
The（）(千斤索) is a wire used to take the weight off.A. lig...
单项选择题The（）(千斤索) is a wire used to take the weight off.
A. light derrick B. union purchase C. topping lift D. heavy derrick
The （）(双杆联吊) is that two booms are used with a single h...
单项选择题The （）(双杆联吊) is that two booms are used with a single hook.
A. derrick B. union purchase C. topping lift block D. crane
