单项选择题
A.VC B.PC C.A+B D.NC
The （）(支索)is important to a derrick.A. blockB. guyC. st...
单项选择题The （）(支索)is important to a derrick.
A. block B. guy C. stay
The （）(吊杆托架) supports the derrick.A. derrick boom restB...
单项选择题The （）(吊杆托架) supports the derrick.
A. derrick boom rest B. derrick head C. derrick mast D. derrick guy
The （）(千斤滑车) can run the gooseneck.A. heavy derrickB. p...
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
