单选题 Five and a half years into his presidency, George Bush finally vetoed a bill this week. Oddly enough, it was one that most Americans support: it would have expanded foderal funding for embryonic stem-cell research. The House and Senate had both passed the bill by wide, but not veto-proof margins, so Mr. Bush's word is final, at least until after the mid-term elections in November.
Stem cells are cells that have not yet decided what they want to be when they grow up. That is, they can become blood cells, brain cells, or pretty much any other type of cell. Their versatility makes them extremely useful for medical research. The ethical snag is that the best stem cells are harvested from human embryos, killing them. For the most ardent pro-lifers, including Mr. Bush and many of his core supporters, that is murder. Proponents of embryonic stem-cell research point out that hordes of embryos are created during fertility treatment, and the vast majority of these are either frozen indefinitely or destroyed. Is it really wrong to use them for potentially life-saving research? Yes, said Mr. Bush on July 19th, flanked by some families who had "adopted" other people's frozen embryos and used them to have children of their own.
Mr. Bush's veto does not kill stem-cell research. Scientists who spurn federal cash may do as they please. The government still pays for research on stem cells taken from adults, a process that does not kill the donor. And a decision by Mr. Bush in 2001 allows federally-funded scientists to experiment on the few dozen embryonic stem-cell "lines" that already existed then, which can be propagated in a laboratory.
Nonetheless, scientists are furious with Mr. Bush. Federal funding would surely push them faster towards those elusive cures. Research based on adult stem cells may be promising, but not nearly as promising as that based on embryonic ones. There are worries that those few dozen embryonic stem-cell lines represent too narrow a gene pool, and that they cannot be endlessly extended without damaging them. Other countries, such as Britain and China, are enthusiastically experimenting on embryonic stem cells. But the world's most innovative nation is hanging back.

单选题 From the first paragraph, we learn that ______.

【正确答案】 B

【答案解析】[直击题眼] 第一段开头：FIVE and a half years…，it was one that most Americans support：it would have expanded federal funding for embryonic stem-cell research．
[深层剖析] 本题是针对文章开头引入话题的现象提出问题的。文章第一句话提到美国总统否定此项法案，而第二句话提到大多数美国人支持此项法案。因此，[B]正确。◆注意：强调句常考。
[主干扰项分析] [A]虽然参众两院均通过了此项法案，但并未获得可以避开总统否决权的多数票。◆谨记：读题一定要细致，尤其是否定处，以免造成不必要的失误。
[次干扰项分析] 参众两院均通过了此项法案，但如果未获得可以避开总统否决权的多数票时，总统就有否决权。故[C]不正确。此否决权不是针对成人干细胞，而是针对胚胎细胞，故[D]不对。

单选题 According to the passage, stem cells refer to ______.

【正确答案】 A

【答案解析】[直击题眼] 第二段开头：Stem cells are cells that have not yet decided what they want to be when they grow up. That is，they can become blood cells；brain cells，or pretty much any other type of cell．
[深层剖析] 本题为定义题，相对比较简单。◆注意：这一类题目要注意文中的that is等，这一点恰恰是定义题的解题技巧。
[干扰项分析]由文中原话即可很容易推知[B]、[C]、[D]均不对。

单选题 The expression "snag" ( Line 3, Paragraph 2) most probably means ______.

【正确答案】 B

【答案解析】[直击题眼] 第二段第四、五句The ethical snag is that the best stem cells are harvested from human embryos，killing them．For the most ardent pro-lifers，including．．．that is murder．
[深层剖析] 本题为词义题，相对比较难，要求考生对文章的内容作细致的理解，推导出词的含义，同时还要对选项的词义熟悉。通过这两句可知很多人对这种研究是反对的，所以能够推出为“反对或问题，障碍”的意思，所以[B]正确。
[干扰项分析]根据对上下的理解可知：[A]、[C]、[D]的说法都不够确切。

单选题 Scientists can go on the stem cell research because ______.

【正确答案】 C

【答案解析】[直击题眼] 第三段：Mr Bush's veto does not kill stem-cell research…．propagated in a laboratory．
[深层剖析] 本题的题干形式在近年考试中出现频率很高，曾在2005年第2篇文章第5题中出现过因果类题型。根据第一句“布什的否决没有彻底封杀干细胞研究”和第四句“2001年布什决定允许联邦资助的科学家们对已存在的一些胚胎干细胞进行实验”可知[C]正确。
[主干扰项分析] 本题[A]选项的干扰性很强，这点虽然文中也提到了，但与题意不符，并不是科学家能继续进行这种试验的原因。
[次干扰项分析] 选择选项[B]和[D]选项的同学是因为在最后一段看到了原句，但它们均不合题意。◆谨记：照抄原文并非答案，同义替换时可为答案。

单选题 It can be inferred from the last paragraph that ______.

【正确答案】 C

【答案解析】[直击题眼] 最后一段：Other：countries，such as Britain and China，are enthusiastically experimenting on embryonic stem cells．But the world's most innovative nation is hanging back．
[深层剖析] 本题考查学生对文章细节及主体脉络的理解，文章最后一段叙述了世界以及美国科学家关于胚胎干细胞实验的态度和发展，根据最后两句可知[D]为正确答案。◆注意：此类型题要熟练把握细节，把握感情色彩词汇。
[主干扰项分析] [A]选项容易误选。最后一段第一句提到了科学家对布什不满，但参众两院通过了此法案是在文章第一段提到的，这属于前面曾经讲过的跨区错误。
[次干扰项分析] [B]选项含有绝对词must，只要文章中没有出现绝对词，那么含有绝对词的选项往往错误。文章倒数第二句谈到embryonic stem cells(胚胎干细胞)，而[D]选项所说的是adult stem cells(成人于细胞)。因此，[D]错误。