I first saw a crayfish (小龙虾) around 2001...

I first saw a crayfish (小龙虾) around 2001. A friend brought one into the office and told me it was a female animal that was reproducing (繁殖) on its own. We realized the new type of animal  was reproducing itself by the millions.

We think that in the 1990s, two crayfish got children either in a pet store or in the wild. Something went wrong and one of the daughters laid eggs without any males. It’s not unusual for such a sudden change like this to happen, but normally, the children can’t live on or reproduce, and the new type won’t spread. For some reason, this daughter and her children did.

In some way, many of the new crayfish appeared in German pet stores. They would naturally increase, and their owners would often set the children free, which let the animals reproduce and spread farther. In 2003, scientists officially proved that animals like crayfish were, in fact, reproducing themselves. They’ve gone from that single female 25 years ago to millions, or maybe billions, of the same crayfish found throughout Europe and Madagascar.

In 2018, we published a map of the clones’ genetic code (克隆类遗传密码图). This type is becoming a really useful tool for researchers like me: We can use crayfish-like animals to study everything from cancer development to the effects of drugs on the brain. Now that we know this code, we can start to try it in the lab. For example, we might try to make these animals grow to larger sizes so people can sell them for food. This is already happening in Madagascar. It turns out that crayfish are pretty tasty. It’s easy to get lots of them too because they grow up in about three months and lay hundreds of eggs. Just put one in a pool and wait.

1.What do people think happened to crayfish in the 1990s?

A. Crayfish’s children could not live on or reproduce .

B. Crayfish got their lives in a scientific way in the lab.

C. A daughter crayfish got a strange ability to reproduce.

D. All animals like crayfish could reproduce themselves.

2.What does Paragraph 3 mainly tell us?

A. The reason why crayfish became pets.    B. The place where crayfish came from.

C. The different ways to raise crayfish.    D. The fact of crayfish’s self-reproduction.

3.The research on the birth of crayfish will be helpful in __________.

① diet    ② medicine    ③ brain    ④ ocean

A. ①②    B. ③④    C. ①③    D. ②④

4.Where could the passage be picked from?

A. a cookbook    B. a science magazine    C. an advertisement    D. a guide brochure