Scientists have created a healthy clone (克隆) of a black-footed ferret (雪貂) by using DNA from a ferret. They call the ferret Ann and she is the first-ever cloned US endangered species (濒危物种).
Every living thing has DNA—a special code that tells it how to grow. Usually an animal gets half of its DNA from its father, and the other half from its mother. Cloning uses the DNA to create a new copy.
By the 1970s, most scientists believed that black-footed ferrets were extinct (灭绝的). In 1981, a group of black-footed ferrets were found in Wyoming. The US Fish and Wildlife Service caught 18 ferrets there and tried to keep and protect them. All but seven died. Now there are between 400 and 500 such ferrets. But Ann is cloned from a ferret that lived over 30 years ago, so her DNA is very different. Scientists hope that this DNA can make future black-footed ferrets much healthier.
Ann is health y now. Soon, she may have some cloned brothers and sisters. And later, she will have babies. Her children will have babies with wild (野生的) black-footed ferrets, her DNA will begin to spread.
27. We know Ann is the name of a(n) ________.
A.plant | B.animal | C.queen | D.scientist |
28. Paragraph 2 is mainly about ________.
A.endangered species | B.scientists’ worries |
C.life in the future | D.DNA and cloning |
29. What does the underlined sentence “
All but seven died.” mean?
A.All of the ferrets died. | B.Only seven of the ferrets died. |
C.7 of the 18 ferrets go on living. | D.All of the ferrets have 7 children. |
30. What do scientists hope?
A.Ferrets will not die. | B.All ferrets have the same DNA. |
C.All animals can be cloned. | D.The cloned ferrets will help save future ferrets. |