胚胎干细胞（embryonic stem cells，ES cells)

It can be inferred from the last paragraph that ______.

A．the House and Senate are furious with Mr. Bush on behalf of the scientists.

B．research based on adult stem cells must be more promising than embryonic ones.

C．many countries, except America, are keen on experimenting embryonic stem cells.

D．the UK is enthusiastic about experimenting on adult stem cells.

A、zygote

B、myocardial cell

C、bone marrow stem cell

D、embryonic stem cell

A、cells isolated from teratocarcinomas.

B、embryonic stem cells derived from the inner cell mass of the mammalian embryo.

C、epidermal stem cells found in the basal layer of the epidermis.

D、human stem cells generated by treatment of mature cell types with a specific combination of transcription factors.

rliest stage of development and can grow into any part of the body.

A．are, are

B．is, is

C．are, is

D．is, are

Scientists can go on the stem cell research because ______.

A．scientists spurn the government and Mr. Bush's veto.

B．other countriesare enthusiastically experimenting on embryonic stem cells.

C．Mr. Bush's veto does not stop stem cell research completely.

D．all the scientists in America are furious with Mr. Bush.

A.a single type of multipotent stem cell found in the bone marrow

B.differentiated cells that first developed in the fetal liver, but now reside in the bone marrow

C.division of differentiated cell types while circulating in the blood

D.stem cells that became committed to each specific blood celll type during embryonic development

On which of the following aspects does Frisen disagree with some radicals？

A．Whether research should be done on embryonic stem cells.

B．Whether research should be done on adult stem cells.

C．When should people expect a drug for Parkinson's.

D．When should clinical trials of stem-cells research begin.

dly enough, it was one that most Americans support: it would have expanded federal 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.

From the first paragraph, we learn that ______.

A．the House and Senate had not only passed the bill widely, but veto-proof margins.

B．most Americans support the bill although George Bush vetoed an opposite bill.

C．Mr. Bush's opinion is still final after the House and Senate had passed the bill by wide.

D．George Bush vetoed the first critical bill for embryonic adult-cell research this week.

that could affect both next fall's Congressional elections and the pre-eminence of US scientists in the worldwide race to turn research on human embryonic stem cells into a therapeutic revolution.

Testimony at a US Senate hearing on 5 March debated a bill proffered by Republican Senator Sam Brownback (Kansas) that would impose criminal penalties on all attempts at transferring a human somatic cell nucleus into a human egg, whether the purpose was to create an infant (usually called reproductive cloning) or to derive embryonic stem cells for disease research (usually called therapeutic cloning.) The US House of Representatives passed a similar total ban last year. Two other bills have also been introduced into the Senate; both would ban reproductive human cloning but permit therapeutic cloning.

Meanwhile, President Bush is expected to fill the long-vacant top job at the National Institutes of Health this week with Elias Zerhouni, executive vice dean of the Johns Hopkins University School of Medicine in Balthnore. For several months the front-runner for NIH director had been AIDS expert Anthony Fauci, head of the National Institute of Immunological Diseases and Stroke. The campaign against Fanci was led by Brownback, who regarded him as insufficiently pro-life. Zerhouni is said to have endorsed Brownbacks anti-cloning bill in writing.

The Bush administration also proposed last week that the United Nations adopt a Brownback type worldwide ban on human cloning, including therapeutic cloning. The UN is considering prohibiting reproductive cloning, but delegates from Europe and Asia oppose interfering with cloning to produce embryonic stem cells for research.

The US Senate hearing starred Christopher Reeve, Hollywood's former Superman, a persuasive high-profile advocate for stem cell research who is handsome as ever, but paralyzed from the shoulders down and unable to breathe on his own because of a riding accident some years ago. Testifying against the Brownback bill, Reeve told the hearing that only human embryonic stem cells carrying his own DNA offered hope for remyelinating his devastated spinal nerves via an immunologically compatible cell transplant. Also testifying against the bill was the hearing's scientific star, Nobel laureate Paul Berg of Stanford University. Berg argued that human stem cells not only could solve the problem of transplant rejections, they also could provide a unique source of information about common chronic late-onset diseases such as cancer. Studying cells from young people carrying mutations that predispose them to complex disorders could illuminate the disease process and generate clues to prevention or cure, he said. As both these applications are based on transfer of particular nuclei into human eggs, he pointed out, none of the existing 78 human embryonic stem cell lines President Bush approved for federally funded research last summer would be useful either for complex disease research or for compatible transplants.

Berg also objected strongly to both the Brownback and the House bills' ban on importing therapies based on human embryonic stem cell research done elsewhere in the world. That would prevent 280 million Americans from taking advantage of treatments developed in nations such as the UK where some of this research is permitted, he pointed out. It might even mean that Americans who seek such treatments abroad could be arrested and fined when they return, he predicted.

Both Reeve and Berg have suggested that a comprehensive ban on human cloning would put US scientists at a competitive disadvantage. The US would take a giant step backward in research leadership, Reeve noted, and anyway the work would be done abroad, for example in Europe. "Those are not rogue nations behaving irresponsibly," he told the Senate. Berg has said that h

A．Both reproductive and therapeutic cloning

B．Reproductive cloning only

C．Therapeutic cloning only

D．Neither reproductive nor therapeutic cloning