全液压钻机的液压传动有哪两个基本特征？
参考答案：
压力按帕斯卡定律传递，其值决定于负载；速度按“容积变化相等”原则传递，其值决定于流量。
Your desk is crowded with too many unnecessary things, including used papers and books.You'd better ________ some of them.[ ]
A. remain
B. resist
C. remove
D. renew
适用于髌骨骨折或鹰嘴骨折的压垫是（）
A.平垫
B.合骨垫
C.抱骨垫
D.葫芦垫
E.大头垫
