问题 选择题

在30℃时,甲、乙两烧杯中分别盛有250g、350g氯化铵饱和溶液,要使两杯析出相同质量的氯化铵晶体,下列措施正确的是

(  )

A.各蒸发掉20g水并恢复至原温度

B.同时降温至10℃

C.甲杯蒸发掉25g水,乙杯蒸发掉35g水

D.同时升高温度至40℃

答案

答案:A

判断题
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Divorce is bad for environment

US researchers raised a new theory on Monday: divorce is bad for the environment.

The global trend toward higher divorce rates has created more households with fewer People,

scientists at Michigan State University reported in the Proceedings of the National Academy of

Sciences.

More households means more houses,fuel and water are Heeded for them,the researchers  wrote.“Globally,the number of households is increasing much faster than the number ofpeople,”said co-author “Jack” Liu in a telephone interview. “Even in regions with declining populationn, we see substantial increase in the number of households. Divorce is the main reason for reducingthe number of people in a household,” he said.

The average divorced person’s household is about 40 to 50 percent smaller than the average married person’s household, Liu said. But whether there are three or six people in a house ,the amount of fuel needed to heat them is about the same. In the United States, divorced households used 74 billion kilowatt—hours of electricity and 2.850 trillion liters of water in 2005, half of which could have been saved if households had stayed the same size as when they were married.

In the United States and 11 other countries between 1998 and 2002, if divorced households had combined to have the same average household size as married households, there could have been 7.4 million fewer households.

The number of divorced households in those countries ranged from 40,000 in Costa Rica to

almost 16 million in the United States around 2000. The number of rooms per person in divorced households was 33 percent to 95 percent greater than in married households.

“If you really want to get divorced, maybe you can remarry with somebody else, or live together with somebody else you like”, Liu said.

1. In America when the number of households is_________, the number of people in a house is__________.

A. increasing, decreasing               B. decreasing, increasing

C. increasing, increasing                   D. decreasing, decreasing

2. What does the word “substantial” in the third paragraph mean?

A. Great        B. Little           C. Sudden                D. Timely

3. How much electricity would have been saved without so many people getting divorced in America in 2005?

A. 7.4 million kilowatt-hours                 B. 16 million kilowatt-hours

C. 37 billion kilowatt-hours             D. about 30 billion kilowatt-hours

4. The last paragraph is the writer’s_________for people.

A. advice            B. encouragement         C. demand          D. order