單項(xiàng)選擇題

The （）(吊桿托架) supports the derrick.

A. derrick boom rest
B. derrick head
C. derrick mast
D. derrick guy

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單項(xiàng)選擇題

The （）(千斤滑車) can run the gooseneck.

A. heavy derrick
B. pulley block
C. topping lift block
D. guy tackle

單項(xiàng)選擇題

The （）(重吊桿) can lift heavy cargo.

A. heavy cargo derrick
B. heavy deck
C. jumbo boom
D. heavy block