影响齿轮()的因素包括齿轮加工精度，齿轮的精度等级，齿轮副的侧_爱下问搜题

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问题单项选择题

影响齿轮()的因素包括齿轮加工精度，齿轮的精度等级，齿轮副的侧隙要求及齿轮副的接触斑点要求。

A、运动精度

B、传动精度

C、接触精度

D、工作平稳性

答案

参考答案：B

单项选择题

酚妥拉明能选择性地阻断（）。

A．M受体

B．N受体

C．α受体

D．β受体

E．DA受体

完形填空

A few years ago, my younger brother and I went to Norfolk, Virginian by plane.       , before we took off, we heard the pilot’s voice throughout the plane, “sorry, ladies and gentlemen. We have no       on the plane. We have a generator(发电机), and we are going to        the engines with it. We will        in the air and head to Norfolk, and see what happens. ”
See what happens? We are going to get up in the air, and see what happens? At this point, one woman started crying. “Oh, no! We are going to       ！” There were sighs of desperation and       spreading throughout the plane, and we hadn’t even        yet. Thirty minutes passed and we were still        there. Then the voice of the pilot came over again,“ Ladies and gentlemen, I know you are       , so we are. We only have one engine going right now, and it is working double time. ”
There was crying       we had walked into grave. But, the pilot told us our one engine was working double time, and his        was to get up in the air and see what happens! Then we did. We got up in the air and         happened. We arrived in Norfolk and everyone        for still being alive.
Although I do sincerely like to have a plan        “see what happens”, which really isn’t such a bad life strategy, all too often, I would see people pursuing their goals        with inaction just because they don’t have        success. Actually, success will never be guaranteed. The       thing that you can do is just get up in the air, and see what happens.
If you are planning to learn a new skill, get up in the air, and see what happens! It might not be as       as you thought. You might be smarter than you thought. It could be        ! So don’t stay there trying nothing just because there is no        of guaranteed success.

C．Unfortunately

A．looked over

D．embarrassed

C．better than

A．interesting

B．challenging

D．encouraging