问题 填空题

使用开普勒望远镜观察远处的物体时,远处物体的光经过物镜后成一个______、______的______像,此像经目镜的作用成______、______的______像.

答案

望远镜由两组凸透镜组成,物镜的作用是使远处的物体在焦点附近成倒立,缩小的实像,相当于照相机的工作原理.

这个倒立缩小的实像正好落在目镜焦距内的位置,目镜的作用相当于一个放大镜,这个实像经过目镜成一个正立、放大的虚像.

故答案为:倒立;缩小;实;正立;放大;虚.

单项选择题
阅读理解

阅读理解。

     Now we’re always hearing about road accident, and when we’re in a car we try to drive carefully, but how many of us take the same degree of care in our homes? Any large hospital will tell you the number of

the accidents that happen in the home is almost the same as those on the road.

     One of the commonest and most dangerous causes of home accidents is wrong and careless use of

electrical equipment. People will continue to use a loose plug or pull out a plug without first turning off the

 power. In spite of warnings, one will carry an electric heater into the bathroom when he is going to have a bath. Sometimes one forgets to cut off the power before mending a lamp or something else. All this will

cause accidents. So the rule about anything that work by electricity is: Switch off before you touch

anything and don’t pretend you know when you actually don’t.

      If you’ve got children in the house, it's always best to keep medicines of any kind out of their reach.

Otherwise, they may be taken for candies or a new kind of drink. When there are older people living with you, you have to take particular care in a number of ways in order to make them safe and happy.

     Fire, of course, is always a risk. So, remember not to dry clothes in front of fires, or leave stoves in the middle of rooms where they can easily be knocked over. And don’t forget to keep the children away from fire. Smoking, too, may cause fire. So you’d better give it up. Safety first may mean a little more time and

care, but it may save you a lot of trouble.

1. According to the writer, we try to drive carefully in a car while __________.    

A. we take the same degree of care in our homes    

B. We don’t care much about the accidents in large hospitals    

C. We don’t pay enough attention to home accidents   

D. We seldom think a lot about the road accidents 

2. We can learn from the text that __________.     

A. people should never be allowed to carry an electric heater into the bathroom   

B. the improper use of the electrical equipment is the most dangerous cause of home accidents    

C. people should cut off the power first before using the electrical equipment    

D. both the children and the older people should be taken special care of at home 

3. It can be inferred in the text that our life at home will be much safer if __________.     

A. we know more about the accidents that happen in the home 

B. all of us give up smoking as soon as possible     

C. we take more time and care in our life  

D. we keep the stoves at the corner of the rooms 

4. The main purpose of writing the text is __________.    

A. to tell how and why home accidents happen   

B. to persuade people to get rid of bad habits    

C. to explain how to use electrical equipment   

D. to instruct people how to prevent home accidents