问题
单项选择题
（）夹具常用的有三爪自定心卡盘、弹簧夹头及双v形架自动定心等装置，这种方法一般用于长圆柱表面定位，可以消除4个自由度。
A.自动定心定位
B.定位套定位
C.V形架定位
D.长圆柱孔定位
答案
参考答案：A
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（）夹具常用的有三爪自定心卡盘、弹簧夹头及双v形架自动定心等装置，这种方法一般用于长圆柱表面定位，可以消除4个自由度。
A.自动定心定位
B.定位套定位
C.V形架定位
D.长圆柱孔定位
参考答案：A
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| When a friend was visiting David, it began 1 . So David told him 2 that night. "You may stay here 3 the night," he said. "OK," answered his friend. But 4 minutes 5 , the friend went out. He didn't tell David where 6 going nor (也没有) did he ask for an umbrella. When David was about 7 , his friend 8 . He was all wet through. "Where 9 you 9 ?" asked David. "I have been 10 ," answered the friend, "to tell my mother that I'll not go home tonight because of the rain." | ||||
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