The police find most criminals (罪犯) because somebody tells them who the criminals are. They find other criminals by using science and their computers. When there is a bank robbery (抢劫), the police first look through their computers for the names of the bank robbers that they know about. Then they go and talk to any of these robbers who are not in prison (监狱). They ask them where they were when the robbery happened. If any of these people cannot give a good answer, the police will often use science to find out if one of them is the robber.

Many criminals leave something of themselves at the places of the crimes like a fingerprint or a hair. Or they take something away on their shoes or clothes, like dirt or animal hair. If they leave behind some of their blood or their hair or a piece of skin, it will have their DNA inside it.

Everyone’s DNA is different and their fingerprints are also different. So, if a criminal cuts himself during a robbery or leaves his hair, or even a small piece of skin, scientists can find out what his DNA is. The police can then ask the person they think is the robber to give them his hair or some blood and see if it has the same DNA. Many criminals are in prison today because of this kind of evidences .

根据上文内容判断正 ( T ) 误( F )

1.Usually the police find criminals because they use their computer.

2.The police do not usually ask criminals who are in prison about a crime because these criminals could not have done it.

3.The most useful evidences that criminals leave at the places of their crimes are things with their DNA in them.

4.Many criminals usually take something away only on their shoes after the crimes.

5.The story is about a bank robbery.

Do you know why different animals or pests(昆虫) have their special colors? Their colors seem to be used mainly to protect themselves.

Some birds like eating locusts(蝗虫),but birds cannot easily catch them. Why? It is because locusts change their colors together with the change of colors of crops. When crops are green,locusts look green. But as the harvest time comes,locusts change to the same brown colors as crops have. Some other pests with different colors from plants are easily found and eaten by others. So they have to hide themselves for lives and appear only at night.

If you study the animal life,you will find the main use of colors is to protect themselves. Bears,lions and other animals move quietly through forests. They cannot be easily seen by hunters. This is because they have the colors much like the trees.

Have you ever noticed an even stranger act? A kind of fish in the sea can send out a kind of very black liquid when they face danger. While the liquid spreads over(散开),their enemies cannot find them. And they immediately swim away. So they have lived up to now though they are not strong at all.

1.From the passage,we learn that locusts ________.

A.change their colors to protect themselves

B.are dangerous to their enemies

C.are easily found by birds

D.are small animals

2.How can pests with different colors from plants keep out of danger?

A.They have the colors much like the enemies.

B.They hide themselves by day and appear at night.

C.They run away quickly.

D.They have to move quietly.

3.Bears and lions can keep safe because ________.

A.they live in forests

B.they have the colors much like the trees

C.they move quietly

D.they like brown and gray colors

4.Why can the fish mentioned(提到) in the last paragraph live up to now?

A.Because they are very big and strong.

B.Because the liquid they send out can help them escape from their enemies.

C.Because they swim faster than any other fish.

D.Because the liquid they send out can kill their enemies.

5.Which is the best title for this passage?

A.Colors of Different Animals and Pests

B.The Main Use of Colors for Animals and Pests

C.The Change of Colors for Animals and Pests

D.Some Animals and Pests

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