单选题 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?

单选题 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
【正确答案】 A
【答案解析】[解析] 见第二段“A laboratory experiment conducted lost fall suggests it may someday be possible．For the first time，…”去年秋季所进行的一项实验研究表明有朝一日这将成为可能。科学家们首次复制或克隆出了人的胚胎。
单选题 The scientists developed their cloning technique to make it easier for childless couples to have babies by in vivo fertilization.
A. Right B. Wrong C. Not mentioned
【正确答案】 A
【答案解析】[解析] 见第四段第—句，“The scientists developed their cloning technique to make it easier…”科学家们发展克隆技术以使那些不能生育的夫妇通过体外受精的方式更容易地拥有小孩。
单选题 After the egg is fertilized the nucleus begins dividing.
A. Right B. Wrong C. Not mentioned
【正确答案】 C
【答案解析】[解析] 该句句意为“卵细胞受精后核开始分裂”，但本文并未提到这点。
单选题 The technique is just used for providing embryos.
A. Right B. Wrong C. Not mentioned
【正确答案】 B
【答案解析】[解析] 见第五、六段，“But the technique could also be used for other purposes．’通常，医生们要植入多个胚胎以期有一个能着床于子宫。克隆胚胎可给他们提供更多的供植入的胚胎。这项技术也可用于其他目的。
单选题 The technique can make a dead person alive.
A. Right B. Wrong C. Not mentioned
【正确答案】 B
【答案解析】[解析] 见第六段第二句，“Parents might freeze embryos cloned from their children…”父母们可以冷冻保存从他们孩子身上克隆的胚胎以便在孩子不幸死亡时取而代之。这些克隆在孩子们需要器官移植时也是理想的供体。
单选题 The ethical dilemmas of cloning has prevented it from further developing.
A. Right B. Wrong C. Not mentioned
【正确答案】 A
【答案解析】[解析] 见最后一段，克隆在道德方面所处的困境尚未充分开展讨论，因为公众认为时机远未成熟。许多人呼吁要在克隆技术滥用前及时加以控制。
单选题 There is a delicately balanced relationship between the state of the pre-germ cell nuclei and the position in which they find themselves.
A. Right B. Wrong C. Not mentioned
【正确答案】 C
【答案解析】[解析] 该句句意是“胚前细胞的状态与其寻找自己的位置间有一个精确的平衡关系”。但本文并未提到这一点。