Suppose you make your parents so happy, they decide to have another baby just like you. It

might be flattering(讨人喜欢的), but how would you feel about having a little brother or sister who is also your twin？

A laboratory experiment conducted last fall suggests it may someday be possible. For the first time ever, scientists made exact copies, or clones(克隆), of a human embryo.

Although the embryos grew for only six days, cloned embryos could theoretically be implanted in a woman's womb(子宫)and develop into normal babies. Or they could be frozen and implanted years later.

The scientists developed their cloning technique to make it easier for childless couples to have babies by in vitro(在体外的)fertilization. In this procedure, sperm(精子) from the man fertilizes an egg from the woman in a laboratory dish.

In most case, doctors must try implanting several embryos before one stays in the womb. Cloned embryos would give them many more embryos to implant.

But the technique could also be used for other purposes. Parents might freeze embryos cloned from their children so that they could be replaced if any of them died. The clones would also be ideal donors if the children needed organ transplants.

Another possibility: Childless couples could go to a bank of frozen embryos and choose a child just like one who's already living. Some people are concerned that these couples might pick only beautiful, successful children.

The ethical dilemmas(困境)of cloning have not yet been discussed fully because the public assumed it was a long way off. Many people are calling for(要求，提倡)controls on cloning immediately before the practice is abused. What do you think？

In an experiment conducted last autumn, scientists made exact copies of a human embryo for the first time.

A. Right

B. Wrong

C. Not mentioned