Scientists have created a healthy clone of a black-footed ferret by using DNA from a ferret that died over 30 years ago. The cloned animal is called Elizabeth Ann.

Large numbers of black-footed ferrets once lived in the American West. The ferrets live mainly on the prairie dogs they catch. But when farmers began killing off prairie dogs, lots of ferrets died, too. By the 1970s, most experts believed that black-footed ferrets were extinct.

Then, in 1981, a group of black-footed ferrets were found in Wyoming. The US Fish and Wildlife Service(USFWS) caught 18 of these ferrets to try to raise them in captivity so that they could be shielded. All but seven died.

At present, there're between 400 and 500 black-footed ferrets remaining. Some are still in captivity. Others have been released into the wild. But all black-footed ferrets living today are related to the seven animals saved from Wyoming.

Normally, when there're large numbers of a type of animal, they have many small differences. The DNA of the animals gets mixed up when different pairs of animals have babies. The small differences in their DNA can help protect the group as a whole. But because all living black-footed ferrets are closely related, they all have similar weaknesses.

But Elizabeth Ann is cloned from an animal that lived over 30 years ago, so her DNA is very different. Scientists hope that when this DNA is mixed back in, future black-footed ferrets will be healthier in general.

Elizabeth Ann was born on December 10, 2020. Blood tests have proven her to be 100% black footed ferret. It's the first native endangered species ever cloned in the US. Elizabeth Ann seems normal and healthy, and enjoys spending her days in her cage.

She won't ever be released into the wild, but soon, she may have some cloned brothers and sisters. And later, she'll probably have babies. Sooner or later, her children will have babies with wild black-footed ferrets, and her DNA will begin to spread.

【小题1】What does the underlined word “shielded” in paragraph 3 probably mean?

A．Donated.

B．Served.

C．Treated.

D．Protected.

【小题2】What is the biggest threat to the captive black-footed ferrets?

A．Their unusual appearance.	B．Their biological weaknesses.
C．Their poor living conditions.	D．Unfriendly human activities.

【小题3】Elizabeth Ann was most probably cloned from a wild ferret that died ______.

A．in the 1960s

B．in the 1970s

C．in the 1980s

D．in the 1990s

【小题4】What attitude does the author hold towards the future of Elizabeth Ann?

A．Uncaring.

B．Doubtful.

C．Dissatisfied.

D．Positive.