问题 问答题

螺杆压缩机有何优缺点?

答案

参考答案:

优点:体积小,重量轻,占地面积小,振动小,结构简单,使用可靠,对液击的耐受性高。缺点:运转时噪音大,辅助设备庞大。

单项选择题
完形填空

It’s very easy to see why people have bad attitudes. A quick look at the news revealing _21___ with crime, war and corruption (腐败) can easily bring us down. Is it possible to _22__ a healthy, happy attitude when surrounded by these negative things?

Sure it is! It is possible to wake up each morning with a good mood and _23__ the day. Having a positive _24__not only allows us to enjoy life more but also _25__ our health and relationships with others.

To lead a happy life, we need to have a positive attitude. We are responsible for our own _26__; other people can’t make us happy. We need to decide to make ourselves happy. This is wonderful because we don’t have to wait around for someone else to do it for us.

We should surround ourselves with __27_ people. We are influenced by those people with whom we spend the most time. When we have positive friends, we become positive. Otherwise, we become _28__.

We should also use positive_29__. A. L. Kitselman once said, “‘I am…’ are powerful words; be careful when you use them.” We need to replace our negative self-talk with positive words. Don’t say “I hate getting up in the morning.” Instead, try to say “I am _30__to see a new day.” Changing our self-talk will lead us to the changes in our behavior.

21. A. affairs         B. questions      C. troubles        D. problems               

22. A. change         B. refuse         C. keep          D. invent

23. A. look forward to        B. look down on    C. look up to      D. look back on

24. A. opinion        B. attitude       C. influence        D. answer

25. A. damages        B. improves       C. affects        D. weakens

26. A. satisfaction      B. decision       C. happiness      D. development

27. A. positive        B. friendly       C. easy-going        D. good-mannered

28. A. anxious        B. nervous       C. satisfied       D. negative

29. A. writings        B. pictures       C. expressions     D. signs

30. A. painful         B. bored         C. thankful             D. surprised