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问题 单项选择题

质量为m，长度为L的均质杆铰接于O点，A端固结一质量为m的质点如图示。当OA杆以角速度w绕O轴转动时，系统对轴O的动量矩的大小为（）。

A.A

B.B

C.C

D.D

答案

参考答案：C

单项选择题

为紧固件打保险的方法常有哪些（）。

A.保险丝、开口销、自锁垫圈、AN316自锁螺帽等

B.普通垫圈

C.至少在每个搭接面上涂—层铬酸锌底层涂料，在涂层潮湿时，用铆钉沾着铬酸锌涂料进行湿铆接

D.高强度垫圈
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单项选择题

I shouldn’t let it bother me. It really doesn’t matter anyway. But it does bother me ! All those people are preparing to (21) a new century, a new millennium (千年) as well. And it just isn’t (22) !
Most of us schedule our lives by the Gregorian (23) . Our years are measured from the (24) of Christ. The first year of the first century is 1, or 1 A.D. The last year of that century is the year 100. Simple Yes! A century is 100 (25) long. A millennium is 1,000 years long, which is (26) ten centuries.
Since the last year of the first century is the year 100, the first year of the (27) century is 101. Follow that pattern, century by century and you’ll get my (28) . The year 2000 is the last year of the twentieth century. After all, (29) thousand means twenty hundreds. Twenty hundred years means twenty centuries. The year 2000 is the (30) , the final, the one that’s still here, year of the twentieth century!!!!
I know, I’m getting too (31) . But it isn’t fair, While most people will really be enjoying this coming (32) celebration, those of us in the know will be yawning. Everyone else will be (33) for the new millennium and we’ll be saying, "It’s not until next year."
I don’t agree with the (34) , "Ignorance is bliss." But in this case, perhaps it’s (35) .

A．hours

B．days

C．months

D．years
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