问题 选择题

一小船在静水中的速度是3m/s,一条河宽60m,河水流速为4m/s,下列说法正确的是(  )

A.小船渡过这条河的最短时间是20 s

B.小船渡过这条河的最小距离是60 m

C.小船运动的最大速度是5 m/s

D.小船运动的最小速度是3 m/s

答案

A、当静水速与河岸垂直时,渡河时间最短,t=

d
v
=
60
3
s=20s.故A正确.

B、因为静水速小于水流速,可知合速度的方向不可能垂直于河岸,则小船不能垂直到对岸,最小距离不会等于60m.故B错误.

C、当静水速与水流速同向,小船速度最大,为7m/s.当静水速与水流速反向,小船速度最小,为1m/s.故C、D错误.

故选A.

阅读理解

阅读理解。

     Some people think that as more and more people have televisions in their homes, fewer and fewer people

will buy books and newspapers. Why read an article in the newspaper when the TV news can bring you the

information in a few minutes and with pictures? Why read a novel when a play on television can tell you the

same story with color, pictures and action? Why read the biographies of famous men and women when a

one-hour-long television program can tell you all that you want to know?

     Television has not killed reading, however. Today, newspapers and magazines sell in very large numbers.

And books of every kind are sold more than ever before. Books are still a cheap way to get information and

entertainment. Although some books with hard covers are expensive, many books are published today as

paperbacks, which are reasonably cheap. A paperback novel, for example, is always cheaper than an evening

at the movies or the theater, and you can keep a book forever and read it many times.

     Books in the home are a wonderful source of knowledge and pleasure and some types of books should be

in every home. Every home should have a good dictionary. Every home should have an atlas (地图集) of the

world, with large clear maps. It might be expensive, but a good encyclopedia is useful, too, because you can

find information on any subject. In addition, it is useful to have on your bookshelves other non-fiction books

such as history books, science textbooks, cook books, books about medicine and health, etc. it is equally

important to have some fiction (小说) on your shelves, too. Then you can relax with a good story, or from

time to time you can take a book of poems off your shelves and read thoughts and feelings of your favorite

poets.

1. Which is usually quicker?

A. To read a biography of a famous person.

B. To watch a television program about a famous person.

C. To read a newspaper or a magazine.

D. To buy a good dictionary at home.

2. What's the Chinese meaning of the underlined word "encyclopedia"?

A. 百科全书

B. 小说

C. 医药卫生

D. 世界地图

3. Which is usually cheaper?

A. A paperback.

B. A hard-cover book.

C. An evening at the movies.

D. All above.

4. Which is the most important to have in your home?

A. Non-fiction books, such as a dictionary and an encyclopedia.

B. Fiction, such as novels, short stories and books of poems.

C. A' mixture of both good non-fiction and your favorite fiction.

D. Some newspapers and magazines of every kind.

5. Which of the following statements best expresses the main idea of the last paragraph?

A. Books in the home are a wonderful source of knowledge and pleasure.

B. We should buy a dictionary and use it for reading.

C. It is useful to have a good encyclopedia on the shelf.

D. Every home should have an atlas of the world.

单项选择题