单项选择题
The （）(千斤滑车) can run the gooseneck.
A. heavy derrick B. pulley block C. topping lift block D. guy tackle
单项选择题 The （）(重吊杆) can lift heavy cargo.
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.
