单选题The President______his deputy to act for him while he was abroad.

单选题The bond of true affection had pulled us--six very different men from six different countries-across Antarctica; we proved in the end that we weren't very different ______ .

单选题David is the ______ holder of the world 5,000-meter race world record, but there is no guarantee that he will win in the Olympic Games.

单选题Hardy's weakness______his apparent inability to control the comings and goings of these divergent impulses and from his unwillingness to cultivate and sustain the energetic and risky ones.

单选题Shopping bags are provided for the customers'______.

单选题British scientists are preparing to launch trials of a radical new way to fight cancer, which kills tumours by infecting them with viruses like the common cold. If successful, virus therapy could eventually form a third pillar alongside radiotherapy and chemotherapy in the standard arsenal against cancer, while avoiding some of the debilitating side-effects. Leonard Seymour, a professor of gene therapy at Oxford University, who has been working on the virus therapy with colleagues in London and the US, will lead the trials later this year. Cancer Research UK said yesterday that it was excited by the potential of Prof. Seymour"s pioneering techniques. One of the country"s leading geneticists, Prof. Seymour has been working with viruses that kill cancer cells directly, while avoiding harm to healthy tissue. "In principle, you"ve got something which could be many times more effective than regular chemotherapy," he said. Cancer-killing viruses exploit the fact that cancer cells suppress the body"s local immune system. "If a cancer doesn"t do that, the immune system wipes it out. If you can get a virus into a tumour, viruses find them a very good place to be because there"s no immune system to stop them replicating. You can regard it as the cancer"s Achilles" heel." Only a small amount of the virus needs to get to the cancer. "They replicate, you get a million copies in each cell and the cell bursts and they infect the tumour cells adjacent and repeat the process," said Prof. Seymour. Preliminary research on mice shows that the viruses work well on tumours resistant to standard cancer drugs. "It"s an interesting possibility that they may have an advantage in killing drug-resistant tumours, which could be quite different to anything we"ve had before." Researchers have known for some time that viruses can kill tumour cells and some aspects of the work have already been published in scientific journals. American scientists have previously injected viruses directly into tumours but this technique will not work if the cancer is inaccessible or has spread throughout the body. Prof. Seymour"s innovative solution is to mask the virus from the body"s immune system, effectively allowing the viruses to do what chemotherapy drugs do—spread through the blood and reach tumours wherever they are. The big hurdle has always been to find a way to deliver viruses to turnouts via the bloodstream without the body"s immune system destroying them on the way. "What we"ve done is make chemical modifications to the virus to put a polymer coat around it-it"s a stealth virus when you inject it," he said. After the stealth virus infects the tumour, it replicates, but the copies do not have the chemical modifications. If they escape from the tumour, the copies will be quickly recognised and mopped up by the body"s immune system. The therapy would be especially useful for secondary cancers, called metastases, which sometimes spread around the body after the first tumour appears. "There"s an awful statistic of patients in the west...with malignant cancers; 75% of them go on to die from metastases," said Prof. Seymour. Two viruses are likely to be examined in the first clinical trials: adenovirus, which normally causes a cold-like illness, and vaccinia, which causes cowpox and is also used in the vaccine against smallpox. For safety reasons, both will be disabled to make them less pathogenic in the trial, but Prof. Seymour said he eventually hopes to use natural viruses. The first trials will use uncoated adenovirus and vaccinia and will be delivered locally to liver tumours, in order to establish whether the treatment is safe in humans and what dose of virus will be needed. Several more years of trials will be needed, eventually also on the polymer-coated viruses, before the therapy can be considered for use in the NHS. Though the approach will be examined at first for cancers that do not respond to conventional treatments, Prof. Seymour hopes that one day it might be applied to all cancers.

单选题The detective had an unusual Uinsight /Uinto criminal’s tricks and knew clearly how to track them.

单选题This university offers a wide variety of high-quality ______ courses for both graduate and undergraduate students.

单选题Her research indicates (what) many adults routinely subscribe (to) some form of what the scholar (calls) "the magical law of (contagion)".

单选题The travel agency has a full program of______, if tourisls wish to visit local places of interest.(2003年上海交通大学考博试题)

单选题If senescence is to be compatible with natural selection, there must be some concomitant benefit associated with it that outweighs its disadvantage. Since Darwinian fitness is measured by total reproduction, the advantage must be that senescence is inextricably tied up with reproductive effort.

单选题He came back later, ______ which time they had left.

单选题What ______ suppose would happen if the director knew you felt that way?

单选题The Quebecois, (partly because of language, and partly because of religion), have (long been considering) (to separate) themselves from (the rest) of the Canadian provinces.

单选题Products sell better if ______.

单选题Because of difficulties in getting a visa, the students had to ______ the idea of applying for study in the United States. A. reduce B. yield C. relinquish D. waver

单选题English primrose need to be grown in rich damp soil with plenty of ______or compost worked into it.

单选题Wolves are said to howl at the moon when it is ______.

单选题When I took out my appointment book and busily ______ it, my client got the impression that I had a busy schedule.