问题 选择题

将装有黑色粉末的试管(试管内不含氧气)加强热后,有红色物质生成,同时产生一种能使澄清石灰水变浑浊的气体.则黑色粉末是(  )

A.氧化铜

B.木炭粉和二氧化锰

C.木炭粉

D.木炭粉和氧化铜

答案

生成的气体能使澄清的石灰水变浑浊,则该气体是二氧化碳;常见的红色的粉末有红磷、铜、氧化铁,黑色粉末加强热会生成红色粉末和二氧化碳,则红色粉末是铜,黑色粉末中含有氧化铜和木炭.

A、氧化铜加热没有新的物质生成,故错误.

B、木炭粉和二氧化锰都是黑色粉末,它们的混合物加热生成锰(银白色)和二氧化碳气体,故选项错误.

C、木炭粉是黑色的,加热条件下生成二氧化碳气体,不会生成红色物质,故选项错误.

D、氧化铜和木炭粉都是黑色粉末,它们的混合物加热生成铜(红色)和二氧化碳气体,故选项正确.

故选D.

阅读理解

阅读理解。

     Most people may not think that there are any problems with watermelons (西瓜), but some Japanese

sellers do. There is often wasted space when they store (贮存) watermelons, because round watermelons

do not sit nicely on shelves. So some clever farmers have solved the watermelon problem. They make their

watermelons grow in square glass boxes so the watermelons become square. The only problem now is the

price. The square watermelons cost about 80 dollars each.

     Many people know the saying "Roses are red, violets are blue, sugar is sweet and so are you". Well, today

the poem needs to change to "Roses are red, roses are blue"! Australian scientists have just recently discovered

that when they put a chemical from a blue flower into a rose, they can create a nearly 100% blue rose. Some

of science's inventions are beautiful, not just useful!

     Since the mid-1990s, many Chinese farmers have had amazing rice harvests. For many years Chinese

scientists have been working on developing new kinds of stronger rice and now they have produced a new

kind, called super rice. Super rice not only can protect itself against insects (昆虫) and diseases, but it also

produces more than any other kind of rice. Today farmers can grow almost one and a half times more rice

than they could grow in the past.

     Doctors might be able to use vegetables to fight cancer now. US scientists have discovered a way to put

a chemical into tomato plants while they are growing. When cancer patients eat the tomatoes, the tomatoes

will fight the cancer in their bodies. These cancer-fighting vegetables are not yet for sale, because scientists

have not finished testing them. If study finds no problems with the tomatoes, then patients can begin to use

this easy and delicious new treatment.

1. The square watermelons look like ____________.

A. B. C. D.

2. __________ find a way to make blue roses.

A. Chinese scientists

B. Australian scientists

C. American scientists

D. Japanese farmers

3. Which of the following is true?

 A. Super rice can keep itself from insects.

B. Blue roses are more beautiful than red ones.

C. The tomatoes can fight many kinds of diseases.

D. The square watermelons cost less than ordinary ones.

4. The main idea of this passage is ____________.

A. how scientists discover new plants

B. how science makes plants produce more

C. how science has changed plants and people's lives

D. how technology makes our world more beautiful

填空题