题目内容
活塞式压气机进气和排气过程中，气体的压力始终保持不变。（ ）
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压气机的定温效率是压缩前气体的状态相同、压缩后气体的压力相同时，可逆定温压缩过程所消耗的功和实际压缩过程所消耗的功之比。（ ）
压气机按定温压缩时，气体对外放出热量，而按绝热压缩时，不向外放热，所以绝热压缩更为经济。（）
真空泵也可以看作为是压气机。（ ）
4 Complete the paragraph with the correct form of the words below.competentdemocraticdonationintenseintimidateprogressiverecruitsophisticatedThere are two big political parties in the United States: the Republican Party, which is traditionally the more conservative of the two, and the Democratic Party, which is said to be more (1)__________. One of the most interesting and (2)_______ moments in American political life is the election campaign which comes before the presidential elections. Both parties need a lot of money to pay for the campaign, for which they rely on (3)__________ made by individuals and organizations.They also need a lot of new (4)________ to work on the campaign. These people are usually young, intelligent and hardworking, (5)__________ in their jobs and not easily (6)__________ , since they are likely to face a lot of problems which have to be resolved quickly. But they also need to be highly (7)____________, to be able to understand what the American people have a(n) (8)__________ right to ask of its government, and to communicate with them through the style and organization of the election campaign.
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