C. the scientists were rewarded and got lots of money

D. many other attempts to clone mammals failed

4. The lamb is the clone of the cell from sheep B because _____ .

A. it provides the egg cell

B. it gives birth to the lamb

C. it provides the nucleus

D. it is a female sheep

5. The sheep that donated the somatic cell most probably lived _____ years．

A.3 B. 6 C. 9 D.12

6. Which of the follow is NOT a problem or danger of cloning mentioned in the text?

A. Evil leaders may want to clone themselves.

B. Animal clones may develop the illness of older animals and may die younger than the donor animals.

C. There are moral objections to cloning human beings.

D. Too much cloning may lead to the destruction of the balance of nature.

7. Which of the following is not an advantage of cloning?

A. Cloning can be used for medical purposes.

B. Large quantities of food can be produced by cloning.