A
In 1996, scientists announced the first successful cloning of a mammal—the now-famous sheep Dolly. The cloning of Dolly made it possible for researchers to try cloning a number of other mammals in this manner.
Pigs
In 2000, PPL Therapeutics , the same company that worked with the Roslin Institute to clone Dolly the sheep, announced that it had cloned five female pigs from adult pig cells. The pigs were named Millie, Christa, Carrel, Dotcom and Alexis.
Cats
In 2001, researchers at Texas A&M University cloned a cat, nicknamed CC. The cat was born on December 22, 2001, to a surrogate(代孕的) mother. CC had her own babies a few years later.
Deer
Researchers at Texas A&M also cloned a white-tailed deer, nicknamed Dewey, in 2003. Dewey was born to a surrogate mother and was cloned from skin cells taken from a dead white-tailed deer. Dewey is still alive today.
Wild goats
In 2009, scientists reported that, for the first time, they had cloned an extinct mammal, the bucardo(a type of wild goat). The group of researchers used cells from preserved samples from a bucardo caught in 1999 to produce the cloned animal. However, the young goat died only minutes after its birth because of problems in her lungs.
21. Which of the following was cloned from a dead animal?
A. Dolly. B. Millie. C. CC. D. Dewey.
22. Why didn’t the bucardo survive after its birth?
A. It couldn’t breathe.
B. It wasn’t born healthy.
C. It wasn’t taken good care of.
D. It was cloned from preserved samples.
23. What is the text mainly about ?
A. Some great scientific breakthroughs.
B. The most famous cloned animals in history.
C. The animals that were born to a surrogate mother.
D. Some mammals that have been cloned since Dolly.
