问题 问答题 简答题

离心式压缩机转子的叶轮作用是什么?

答案

参考答案:

转子的叶轮又称工作轮,是压缩机转子上最主要的部件,其作用是对气体作功,使气体同叶轮一起高速旋转,在旋转离心力的作用下向叶轮出口流动,并受到叶轮流道的扩压作用,在叶轮出口处气体的压力和速度均得到提高。

填空题



Most taxpayers have had enough income tax collected by their employers during the year. So they do not (36) any money. In fact, most Americans get some money back. Last year, the Internal Revenue Service returned at least some money to more than (37) Americans paying individual income tax.
The United States has what is called (38) . Tax rates increase as (39) increase. This year, people earning more than (40) are taxed at the highest rate.
Earnings above that amount are taxed at (41) . Earnings below that amount are taxed at lower rates.
Individuals who earn less than (42) pay no income tax. But they do pay (43) , Medicare and other taxes.
There are many different ways for people and businesses to reduce their (44) Most homeowners, for example, can reduce their taxes a little by reporting to the I.R.S. the interest they pay (45) . This is called a (46)
In 2004, personal income taxes provided the government with most of its money: (47) of the budget. Social security and other (48) taxes provided (49) . Other forms of income include (50) , money borrowed to (51) and special taxes on (52) .
But income from taxes did not provide enough to pay for government spending. The I.R.S. says the budget deficit for 2004 was about (53) dollars.
Preparing tax documents can be complex. The I.R.S. estimates that taxpayers need an average of about 13 hours to prepare tax documents. And that is just for the basic tax form. For business, the I.R.S. estimates an (54) needs more than 50 hours. This is why a lot of Americans pay (55) to complete their tax documents for them.

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