Since I was born and brought up in a rural town，I have a great interest in nature.Using the chance of studying abroad in my second year at college，I decided to go to Canada just because I wanted to see the beautiful phenomena there.So after I finished the study，I went to Yellowknife in the Northwest.
   I clearly remember the sixth night in Yellowknife.Suddenly my host mother came to my room around 8 p.m.and told me to change clothes and go outside quickly carrying her camera.
   The northern lights were flickering（閃爍）in the sky!I was amazed and just stood there with my mouth open.I forgot to take pictures of the mysterious lights.
   Since that night，whenever it was sunny，I went outside at night and looked at the sky.It was so cold that my hands and feet were numb with cold.Actually，the time of my being able to be out was limited.I had to bring her camera back to the house in one hour at the most，for the camera was going to be broken because of the cold temperature.
   As I took pictures of the northern lights，I came to find a characteristic movement of the lights.They first appear in the north part of the sky and then they gradually come down to the south.After that，suddenly，they come in the middle of the north and south only for a while，which is the time when the best northern lights can be seen.Since it is only a few seconds for the northern lights to come down to the middle of the sky，it is very hard to get good pictures.
   The stronger the sun acts，the better and stronger northern lights flicker in the sky.That's because they occur from the collision（碰撞）between atmospheric gases and solar wind.Much more solar wind comes to the earth when the sun is active，leading to the best northern lights.

（1）Why did the author forget to take pictures？

B

B

A．It was freezing cold outside.
B．He was shocked by the wonderful sights.
C．The lights were flickering in the sky.
D．He lost all his feeling in his hands and feet.
（2）What can we infer from the passage？

D

D

A．The northern lights came out every night.
B．The author took lots of pictures with his camera.
C．The author could stay as long as he liked outdoors.
D．Cameras will be damaged if exposed too long to coldness.
（3）When is the best time to see the northern lights？

C

C

A．They appear in the north part of the sky.
B．They rise in the east and set in the west.
C．They are between the north and south.
D．They come down to the south part of the sky.
（4）Why is it hard for the author to take good pictures？

A

A

A．The lights stay in the middle for a very short time.
B．The lights of the sun affect the northern lights.
C．The lights are caused by the collisions of gases.
D．The colours of the lights are determined by the height.