问题 选择题

下列制取硫酸铜的实验设计中,能体现“经济、高效、环保”精神的最佳方案是(  )。

A.铜与浓硫酸共热

B.用铜片为阳极,石墨为阴极,电解稀硫酸

C.先灼烧废铜屑生成氧化铜,然后再用浓硫酸溶解

D.适当温度下,使铜片在持续通入空气的稀硫酸中溶解

答案

答案:D

A项有SO2生成;B项耗能较多;C项也耗能过多。

阅读理解

When people communicate, they need words to express themselves. People living in different countries made different kinds of words.

Today there are about fifteen hundred languages in the world. Each contains many thousands of words. A very large dictionary, for example, contains four or five hundred thousand of words. But we do not need all these. To read short stories you need to know only about two thousand words. Before you leave school, you will learn only one thousand or more.

Vocabulary means a lot of words. The words you know are called your vocabulary. You should try to make your own vocabulary bigger. Read as many books as you can. There are a lot of books written in easy English for you to read. You will enjoy them. When you meet a new word, find it in your dictionary. Your dictionary is your most useful book.

小题1:The number of different languages spoken is about _______.

A.150

B.15,000

C.500

D.1,500小题2: Before you leave your school, you’ll learn _______.

A.only two thousand words

B.five hundred thousand words

C.more than one thousand words

D.three or four thousand words小题3: To make your vocabulary bigger, you must _______.

A.get as many dictionaries as you can

B.read as many books as you can

C.buy a lot of books

D.have a very large English dictionary小题4:You will enjoy_______.

A.the books written in easy English

B.your dictionary

C.your new words

D.finding new words in a dictionary小题5: What is your most useful book?

A.Books written in easy English.

B.Books written in English.

C.Your dictionary.

D.Short stories.

单项选择题