常見例句雙語(yǔ)例句The derrick man, positioned at the crown block, is to advise the driller when the snake is coming through the crown sheave.井架工看守在天車上，當(dāng)蛇皮接繩器到達(dá)天車時(shí)，通知司鉆。blog.sina.com.cn 返回 derrick block