问题 选择题

下表列出了除去物质中所含有少量杂质的方法,其中错误的是(  )

选项物质所含杂质除去杂质的方法
ACOCO2通入足量的氢氧化钠溶液,干燥
BNaCl泥沙加入足量的水溶解、过滤、蒸发
CNaOH溶液Na2CO3加入足量的稀盐酸至不再产生气泡
DFeCl2溶液CuCl2加入过量的铁粉,过滤

答案

答案:C

题目分析:A氢氧化钠可除去二氧化碳,再经过干燥可得到纯净的一氧化碳。此项正确。B泥沙不溶解于水,可过滤除去。再通过蒸发滤液可得到纯净的氯化钠。此项正确。C稀盐酸可与氢氧化钠、碳酸钠两种物质均发生反应,此项不正确。D氯化铜溶液可与铁反应生成氯化亚铁,再过滤即可得到氯化亚铁溶液。此项正确。所以应选C项。

阅读理解

Five years ago, David Smith wore an expensive suit to work every day. “I was a clothes addict,” jokes. “I used to carry a fresh suit to work with me so I could change if my clothes got wrinkled.” Today David wears casual clothes---khaki pants and sports shirt---to the office. He hardly ever wears necktie. “I’m working harder than ever,” David says, “and I need to feel comfortable.”

More and more companies are allowing their office workers to wear casual clothes to work in the United States. The change from formal to casual office wear has been gradual. In the early 1990s, many companies allowed their employees to wear casual clothes on Friday (but only on Friday). This became known as “dress-down Friday” or “casual Friday.” “What started out as an extra one-day-a-week benefit for employees has really become an everyday thing,” said business consultant Maisly Jones.

Why have so many companies started allowing their employees to wear casual clothes? One reason is that it’s easier for a company to attract new employees if it has a casual dress code. “A lot of young people don’t want to dress up for work,” says the owner of a software company, “so it’s hard to hire people if you have a conservative dress code.” Another reason is that people seem happier and more productive when they are wearing comfortable clothes. In a study conducted by Levi Strauss and Company, 85 percent of employers said that they believe that casual dress improves employee morale. Only 4 percent of employers said that casual dress has a negative impact on productive. Supporters of casual office wear also argue that a casual dress code helps them save money. “Suits are expensive, if you have to wear one every day,” one person said. “For the same amount of money, you can buy a lot more casual clothes.”

小题1:David Smith refers to himself as having been “a clothes addict” because_______.

A.he often wore khaki pants and a sports shirt

B.he couldn’t stand a clean appearance

C.he wanted his clothes to look neat all the time

D.he didn’t want to spend much money on clothes小题2:David Smith wears casual clothes now, because________

A.they make him feel at ease when working

B.he cannot afford to buy expensive clothes

C.he looks handsome in casual clothes

D.he no longer works for any company小题3:According to this passage, which of the following statements is FALSE?

A.Many employees don’t like a conservative dress code.

B.Comfortable clothes make employees more productive

C.A casual clothes code is welcomed by young employees

D.All the employers in the U.S are for casual office wear.小题4:In this passage, the following advantages of casual office wear are mentioned EXCEPT_______.

A.saving employees’ money

B.making employees more attractive

C.improving employees’ motivation

D.making employees happier

多项选择题