问题 单项选择题

某城市给水排水管道工程由某工程公司承包。该工程施工单位在排水工程中采用柔性管道。在管道安装过程中,部分工作方法如下:
(1)下管前,对产品按产品标准逐节进行了外观质量检验,符合标准要求;
(2)下管时,采用人工下管;
(3)塑料管材的接口,采用了弹性密封橡胶圈连接的承插式柔性接口。

管道接口用的弹性密封橡胶圈应采用氯丁橡胶或其他具有耐酸、碱、污水腐蚀性能的合成胶,下列选项中对其性能的要求不正确的是( )。

A.邵氏硬度:50±5

B.伸长率:≥500%

C.永久变形:<25%

D.老化系数:≥0.8(70℃,144

答案

参考答案:C

选择题
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.