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
查看答案
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.
What did his parents do after he lost his arms?
A. They gave up on him.
B. They encouraged him to learn to take care of himself.
C. They did everything for him to take good care of him.
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