1. (2020八下·淅川期末) 阅读理解

    People and dogs have been living together for a very long time. When did dogs and people become friends? Where did dogs come from?

    A group of scientists tried to answer these questions. They just did a study about the history of dogs. In the study, they looked at the DNA of dogs all over the world and found that dogs, like humans, shared DNA with their relatives(亲戚). The scientists put together a big family tree for dogs.

    It went all the way back to the animal' beginning.

    In this way, scientists learned about the history of dogs. The first dogs lived in Asia. They were born about33, 000 years ago. At first, there were only about 6, 400 of them. Their parents were wolves (狼）.

    The new study answers many questions. It brings some, too. For example, what caused wolves in Asia to become dogs all those years ago?

    One idea is that their DNA slowly changed and the wolves became dogs in the end. And later dogs became "man's best friend". Or it could happen the other way around. It was possible that some wolves started living with people before they became dogs. Living with people led to many changes to these wolves. It changed their DNA, so their offspring(后代)became dogs.

    By studying DNA, scientists now have a much better understanding of the history of dogs.    ▲      How exactly dogs came to be our friends is still unclear.

1. （1） The scientist looked at the DNA of dogs because ______________.

   A . they wanted to change dogs' DNA. B . they wanted to know more about dogs. C . they wanted to put a big family tree for dogs. D . they wanted to find some new questions about dogs.
3. （2） Which of the following is TRUE about the first dogs?

   A . They lived in Africa. B . There were about 33, 000dogs. C . They were born 6, 400 years ago. D . They were the offspring of wolves.
5. （3） According to the second idea in Paragraph 5, wolves____________.

   A . didn't want to become dogs. B . spent a long time living with dogs. C . became dogs before they changed their DNA. D . were man's friends before they became dogs.
7. （4） Which of the following can be put in_____________________?

   A . And we can know dogs' birth place. B . However, there is still much to learn. C . But we still know little about wolves' habits. D . So they can explain when dogs became our friends.
9. （5） What can we learn from the passage?

   A . Wolves and dogs are friends all he time. B . Dogs' DNA isn't similar to wolves' any more. C . People had a hard time making friends with dogs. D . Scientists can't answer all the questions by studying dogs' DNA.