液压缸差动联接是将单活塞液压缸活塞杆液压缸的两腔同时接入压力油的联接方式。当要求快进速度为工进速度的2倍时，活塞杆径d和液压缸径D的关系约为d = （）D。
A. 0.5
B. 0.6
C. 0.7
D. 0.8
采用缸筒固定安置，工作台的移动范围为活塞有效行程的（）
A. 1倍
B. 2倍
C. 3倍
D. 4倍
How did Liu Wei lose his arms?
A. He touched a high-voltage wire during a game.
B. He played hide-and-seek with his friends and fell from a high place.
C. He was caught in a fire accident.
微信支付 
支付宝支付