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问题 单项选择题

滚珠丝杠副采用双螺母齿差间隙方式时，如果最小调整量S为0.0025mm，齿数Z＝60，Z2＝6，则滚珠丝杠的导程L0为（）

A.4mm；

B.6mm；

C.9mm；

D.2mm

答案

参考答案：C

阅读理解

Many students get ill easily .They have to go to hospital and may miss a lot of classes. What can we do to keep healthy? Here are some tips:

Healthy food. You should eat less fast food but more vegetables and fruit. You’d better drink 500 ml milk every day .Remember to eat breakfast.

Enough exercise. Doing exercise is important. It makes you more athletic .You can play some sports after class or on weekends.

Happy smiles. Smile is a good way to make you healthy .Try to find things that can make you laugh .Remember that smile is the best medicine to cure(治疗)your illness.

Good rest. If you want to get a good grade ,you must have a good rest .As a famous saying goes, “Early to bed and early to rise makes a man healthy ,wealthy（富有的）and wise（聪明的）.

小题1:将划线句子翻译成汉语。_______________________________________.

小题2:完成下列句子，每空词数不限。

If you get ill, you have to __________________________and may __________________.

小题3:完成下列句子，每空词数不限。

You can play sports_________________ or___________
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填空题

链传动适合于两轴（），中心距较远，传递功率（），且平均传动比准确的场合。按其用途不同，链可以为（）三类。
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