问题 选择题

某研究性学习小组,设计了验证锌、铁、铜三种金属活动性的实验,每种方案如下(反应所得的产物可用作试剂进一步反应),不可行的方案是(  )

A.锌、硫酸铜、硫酸亚铁

B.铁、硫酸铜溶液、硫酸锌溶液

C.锌、铜、硫酸亚铁溶液

D.铁、铜、硫酸锌溶液

答案

A、锌与硫酸亚铁反应可验证锌的活动性比铁强,同时又可得到金属铁,然后用铁跟硫酸铜反应,可验证铁比铜的活动性强,故A是可行的方案.

B、铁与硫酸铜反应,可验证铁的活动性比铜强.铁与硫酸锌不反应,可知铁的活动性比锌弱.故B是可行的方案.

C、锌与硫酸亚铁反应,可验证锌的活动性比铁强.铜与硫酸亚铁不反应,可知铜的活动性比铁弱.故C是可行的方案.

D、铁,铜都与硫酸锌溶液不反应,可知锌的活动性最强.但是铁、铜的活动性无法比较.故D不可行.

故选D.

选择题
阅读理解

The world’s population continues to grow. There are about five billion of us on earth now. It could reach six billion in 10 years’ time, and eleven billion in another 75 years. Experts have long been concerned about such growth. Where will we find the food, water, jobs, houses, schools and health care for all these people?

A major new study shows that situation may be changing. A large and rapid drop in the world’s birth rate has taken place during the past 10 years. Families generally are smaller now than they were a few years ago. This is happening in both developing and industrial nations. Scientists said they found a number of reasons for this. More men and women are waiting longer to get married. More women are going to school or working at jobs away from their home instead of having children. And more governments, especially in developing nations, now support family planning programs to reduce population growth.

China is one of the nations that have made great progress in reducing its population growth by about one half since 1970. China now urges each family to have no more than one child. And it hopes to reach zero population growth before long, that is, the number of birth equaling the number of death.

Several nations in Europe already have fewer births than deaths. Experts said that these nations could face a serious shortage of workers in the future.

1. In the sentence “Experts have long been concerned about such growth”, the phrase “concerned about” is similar in meaning to_____.

A. worried about      B. related to       C. busy working on     D. made a study of

2. “Family planning programs” means______.

A. economic policy in a country         B. economic policy in a family

C. TV programs for a family            D. birth control in a country

3. The world’s birth rate has dropped because_____.

A. people marry at a much later time

B. women would rather go to study or work than have children

C. some countries are carrying out the family planning programs

D. all the above

4. We hope that soon the number of birth and the number of death in China will_____.

A. be greatly different          B. be equal to each other

C. drop in great deal            D. become much larger