--- What do you enjoy most ____ in the summer holidays?

　　　　--- Playing table tennis.

　　A. killing time 　　　　　　　B. to kill time

　　C. spending the time　　　　　D. to spend the time

　　Rats eat our food or make it so dirty that it isn't fit for people at all. That's why people often kill them by laying down poison. After a day or two, they find the poison still there. The rats haven't touched it, even though it is near the food which they eat. People think they must be clever and cunning. Some scientists have been trying to find the best way to poison rats. They have watched to see just what a rat does day and night. They have found out that rats aren't so clever. They are just very shy.

　　Rats usually live in holes. They run from these holes to the places where they eat and drink. They have special paths on which they travel each time. So they know their paths quite well.

　　If anything new, such as stone or wood, is put in the path, the rats won't go near it at first as they are too frightened. It will take them many days to get over the fear. They are also frightened to go near a place that they know, where something has been taken away. If a path goes around a rock, the rats follow the same path around the rock each time. If the rock is taken away, they will still run round the place where the rock was! They won't cross the empty place, which is now open to them, even though it would be quicker.

　　Rats will always keep away from anything unusual to them. That's why they won't eat poison on the first or second night. They usually won't go anywhere near it for about four days until they get used to being there. Even then they only eat a little at a time.

　　If people want to kill rats with poison, all they have to do is to leave it out for a few days. Once the rats have got used to it, they will eat it and die.

　　1．This passage mainly tells us

　　　　A. how a rat destroys our food

　　　　B. how to poison a rat

　　　　C. what's a rat's habit

　　　　D. poisoning a rat is not easy

　　2．How does the writer feel about rats?

　　　　A. They are clever and cunning.

　　　　B. They are the most dangerous enemy.

　　　　C. They are smart and shy.

　　　　D. It's easy for them to get close to an unknown object.

　　3．________ rats have special paths to travel each time.

　　　　A. Because they live in holes most of the time

　　　　B. To find more food to eat and water to drink

　　　　C. In order not to eat anything poisonous

　　　　D. To protect themselves

　　4．If you want to kill a rat, ________.

　　　　A. you should make it get used to the poison

　　　　B. you should drive it out of the hole

　　　　C. you should place a rock on the path along which it runs

　　　　D. you should make it get over the fear to cross the empty place