问题 填空题

一个体积为8cm3的正方体的顶点都在球面上,则球的表面积是______cm2

答案

正方体体积为8,可知其边长为2,体对角线为

4+4+4
= 2
3

即为球的直径,所以半径为

3
,表面积为4π 
3
2
 =12π

阅读理解

阅读理解。

     Which country grows the most tea? The answer is India.  It grows three times as much as China. Which country drinks the most tea? It's neither China nor Japan. It's Great Britain.

     In the wild, tea plants may be 30 feet tall. But a plant grown for market is pruned(修剪).Pruning keeps the plant only three or four feet tall. This is an easy height for tea picking. Only the two top leaves of each

new shoot(芽)are picked. So to make money, tea plantations must be huge.

     In general, there are two kinds of tea, black tea and green tea. They are made in different ways. When black tea is made, it loses nearly all of its healthy qualities.  But green tea retains its healthy qualities. For

instance, it may prevent heart disease(病).

     How did we get tea bags? The answer: by accident. People used to send tea in tin boxes.  This was

expensive. Someone thought of a cheaper way. He sent tea in small silk bags. Customers would open the bag. They would put the leaves into a pot as usual. One customer put the bag into a pot. Then he just

poured hot water over it. And the tea bag was born.

     Shen Nong was the first to drink tea. This was about 2737 B.C.Shen was ill, so he drank several cups of hot water daily. One day something happened.  Leaves from a wild tea tree fell into the hot water pot.

The next cup was poured. The water was now colored. Shen tasted it.  He liked it.  He drank it all. Shen was proud of his new drink. He served it to his guests. World spread. People thought this way. Tea is

good enough for the emperor. So it must be good enough for the people. Tea became the drink of China.

1. The best title for this passage might be______.

A. An Ancient Drink

B. Green Tea

C. A Favorite Drink for Centuries

D. Tea Plant

2. The author's main purpose in writing this passage is to______.

A. persuade you

B. make you laugh

C. tell you how to do something

D. give you information

3. In this passage "retains" means "______".

A. keeps

B. makes

C. takes

D. loses

名词解释