(B)

    Only one man seems to have ever been cured of AIDS, a patient who also had leukemia. To treat the leukemia, he received a bone marrow transplant in Berlin from a donor who, as luck would have it, was naturally immune to the AIDS virus. If that natural mutation could be mimicked in human blood cells, patients could be endowed with immunity to the deadly virus. But there is no effective way of making precise alterations in human DNA. That may be about to change, if a powerful new technique for editing the genetic text proves to be safe and effective. At the University of Pennsylvania, Dr. Carl June and colleagues have used the technique to disrupt a gene in patients’T cells, the type attacked by the AIDS virus. They have then infused those cells back into the body. A clinical trial is now under way to see if the treated cells will reconstitute a patient’s immune system and defeat the virus. The technique, which depends on natural agents called zinc lingers, may revive the lagging fortunes of gene therapy because it overcomes the inability to insert new genes at a chosen site. Other researchers plan to use the zinc finger technique to provide genetic treatments for diseases like bubble-boy disease, hemophilia and sickle-cell anemia. In principle, the zinc finger approach should work on almost any site on any chromosome of any plant or animal. If so, it would provide a general method for generating new crop plants, treating many human diseases, and even making inheritable changes in human sperm or eggs, should such interventions ever be regarded as ethically justifiable.

   Zinc fingers are essential components of proteins bused by living cells to turn genes on and off. Their name derives from the atom of zinc that holds two loops of protein together to form a “finger”. Because the fingers recognize specific sequences of DNA, they guide the control proteins to the exact site where their target gene begins. After many years of development, biologists have learned how to modify nature’s DNA recognition system into a general system for manipulating genes. Each natural zinc finger recognizes a set of three letters, or bases, on the DNA molecule. By stringing three or four fingers together, researchers can generate artificial proteins that match a particular site. The new system has been developed by a small biotech company, Sangamo BioSciences of Richmond, Calif., and, to some degree separately, by academic researchers who belong to the Zinc Finger Consortium. “We now have a full alphabet of zinc fingers,” Mr. Lanphicr, head of Sangamo, said, “but when we started the company it was like typing a novel with two fingers.” Zinc finger proteins have many potential uses. One is to link them to agents that turn on or turn off the gene at the site recognized by the fingers.

The passage mainly discusses_______.

    All the latest footwear engineering in your running sneakers might not mean a thing when it comes to preventing injuries. The latest barefoot running study in the journal Nature deployed 3-D infrared tracking to gauge the difference in foot strike between shod and shoeless runners. Scientific American reports.

   Runners who wore sneakers ended up landing heel-first 75 to 80 percent of the time. By contrast, barefoot runners usually land toward the middle or front of the foot—a dramatic difference that recalls the more natural foot strike of early Homo sapiens. Needless to say, early humans certainly were not bom to run wearing Nike or Reebok.

   “Most people today think barefoot running is dangerous and hurts.” said Daniel Lieberman, a professor of human evolutionary biology at Harvard University and lead author on the study. “But actually you can run barefoot on the world’s hardest surfaces without the slightest discomfort and pain.”

    More bad news for sneakers came last December, when the American Academy of Physical Medicine and Rehabilitation found that running shoes can increase joint torques at the hip, knee and ankle. Their study suggested that even going for a run in high heels was better for preventing joint injuries than tennis shoes.

My View on Low-carbon Economy

accessible

perceive

beyond one’ comprehension

elucidate

take...for granted

41、经济危机之后，人们认为他们的房价不会再继续升高。

42、虽然他是我们大学的校长，但他对学生总是平易近人。

43、我不懂，你得解释一下。

44、我认为他肯定认识我。

45、我不明白她怎么能在一天内做那么多事情。

The urban poor gained from the lower prices and greater supplies of food but the rural poor, especially the landless, have sometimes been disadvantaged. However, new agricultural technology should not be expected to stand proxy for social reform, and Lipton concludes that the technology per se (本身)was not to blame for the inequalities of impact; it met the criteria he would have specified for a technology to help the rural poor. As Frankel commented: ‘It is precisely the social blindness of modem technology that is encouraging the most disadvantaged scciion of the agricultural community’.

television   because    first    movies   keep   owned    hardly   middle  program    American

    Television has certainly changed American life, but not the way the first critics predicted. The (31) televisions were enormously expensive, so most families (32) only one. By 1975, however, 60% of (33) families owned two televisions or more; some (34)class families had as many as five (35) sets under one roof. Such multi-set families may (36) family members in the same house, but that (37) brings them “together.” In fact, family outings—hiking, going to the (38), going out to dinner—are often limited by TV (39) one or more family members don’t want to go: “I’ll miss my (40),” is the common complaint.

Tonight’s TV program________health care reform.

Her husband________her wishes that he stop drinking.

The congress opened with a minute’s silence________those who died in the earthquake.

The future of the island is_______the fortunes of the local government.

________problems may delay the opening of the conference.