问题 选择题
已知函数y=ax的反函数的图象过点(9,2),则a的值为(  )
A.3B.-3C.log29D.
1
3
答案

依题意,点(9,2)在函数y=ax的反函数的图象上,

则点(2,9)在函数y=ax的图象上

将x=2,y=9,代入y=ax中,

得9=a2

解得a=3

故选A.

阅读理解

There are many kinds of food in the world. Scientists learn a lot about them. They say that there are some kinds of food people must eat every day. For example, people must eat some green and yellow vegetables. We shouldn't eat too much meat. People also need to eat some fruits, bread and rice. Of course our bodies need some water and milk.

Scientists say people in different countries and different places eat different kinds of food. They cook food in different ways. Different people eat at different times. In one place, people eat once or twice a day. But in another place, people eat three or four times. The scientists say when to eat and how many times to eat are not important. What we eat is the most important thing.

Nowadays(现在), the world faces two problems. People in some places, for example, in Africa, are not full. Many people are eating junk food. It's bad for people's health. So it's our duty to make everyone full and make everyone healthy.

小题1:            know about food most according to the passage.

A.Farmers

B.Cooks

C.Scientists

D.Doctors小题2: Scientists think the most important thing about food is             .

A.how to cook

B.when to eat

C.what to eat

D.how often to eat小题3: Which of the following statements(陈述) is NOT true?

A.Every day, we should eat some vegetables.

B.All the people in the world have enough food to eat.

C.Many people are eating unhealthy food.

D.Everyone is needed to help solve (解决) the two problems.小题4:            is not good for our health.

A.Water

B.Bread

C.Milk

D.Junk food

选择题