单选题All matter, ______, is made up of atoms.

单选题Passage Four Despite their names, satin and soman are exceptionally ugly sisters. They are organophosphorous nerve gases. They are cheap and simple to manufacture. And mere milligrams—just a drop—of either is enough to kill an adult in a couple of minutes. They therefore make particularly fine weapons of mass destruction, equally popular with rogue dictators who have not been able to build nuclear bombs and with weird cults such as Aum Shinrikyo, which gassed the Tokyo subway in 1995. Detecting them soon enough to prevent their effects can be difficult. Even detecting them after the event—if you are, for example, a United Nations weapon inspector—can be haphazard. But help may be at hand. A paper in this month's edition of Analytical Chemistry, by George Murray and his team at John Hopkins University's Applied Physics Laboratory in Laurel, Maryland, reports a new way of picking up minute qualities of the two gases without the risk of false alarms from legitimate organophosphorous compounds such as insecticides. Dr Murray's detector consists of a fiber-optic cable that has one end plugged into a laser and the other coated with a metal called europium. The laser generates blue light, and europium has the property of shining red when exposed to blue light of the correct wavelength—an effect that is exploited in many optical devices. But the metal possesses a second property that makes it uniquely suitable for Dr. Murray's purpose: it reacts strongly with organophosphates, and when it does so, the wavelength of the light that is emitting changes perceptibly. To stop his detector going off in response to the wrong signals such as insecticide on the flea collar of a dog, Dr Murray has resorted to a second trick. The europium is embedded in a plastic film that binds specifically to sarin or soman (they are very similar molecules), using special pockets called molecular imprints that have been chemically etched into it. The organophosphates commonly used as pesticides do not fit into these pockets; and so fail to react with the metal. The result is a detector that is both sensitive ( it can pick up concentrations of as seven nerve-gas molecules in a trillion) and reasonable fast (it is able to sound the alarm within 30 seconds). So far, Dr Murray has tested his device only on soman dissolved in water. This is mainly a safety measure, because water-borne nerve agents are easier to handle than those in gaseous form. But soman or sarin-contaminated water supplies are a real hazard in themselves—and not just in far-flung war zones. In America, for example, there are occasional leaks from military bases. The most recent was from Tooele Chemical Disposal Facility in Utah, one of the sites where the country's chemical weapons stockpile is being destroyed. At the moment it would be hard to work out if any material from such a spill had found its way into the water supply until people started to become ill. Dr Murray seems confident, however, that his technology will work just as well on sarin and saman gas, and has prepared "smart" cards coated with the mixture of europium and plastic to detect airborne nerve gases. Unfortunately, he does not, at the moment, have access to any place where the safety regulations will permit him to try them out. But if UN inspectors were ever allowed back into Iraq, he might have a chance.

单选题The wide variation ______ prices for some brands cannot be explained by these factors.

单选题The native opposition to authority began at midnight, when a gang of youths massacred the Newton family and set the house afire.

单选题For all their Continental______, Europeans can be remarkably lax about e-mail security.

单选题I never think of fall ______ I think of the hardships I have experienced when I was a child.

单选题After studying in a medical school for five years, Mary ______ her job as a physical therapist in the countryside. A. set out B. took over C. took up D. set up

单选题The Vatican condemned the technology as ______. A. instructive B. perverse C. rewarding D. salutary

单选题There are certain pairs of words which illustrate the way in which sexual connotations are given to feminine words while the masculine words retain a serious businesslike ______.

单选题What you should say in your speech is entirely______you.

单选题The discount of 9% agreed upon was granted only ______ no balance was outstanding from previous accounts.

单选题It is ______my power to solve this problem.

单选题Invasive weeds are a serious problem in Australia Weeds【C1】______the biodiversity of Australia's unique waterways, National Parks, and National Heritage listed areas. By out-competing native plant species, weeds threaten their survival and reduce the plant diversity needed to【C2】______indigenous insects, birds and animals. Changes to the natural flora cover can【C3】______other negative environmental impacts, including increased soil erosion and greater bushfire intensities that further damage the land and the native organisms that【C4】______ it. Agriculturally, weed species can reduce or contaminate crop yields【C5】______poison or injure livestock, decreasing productivity. Farmers are often forced to invest significant amounts【C6】______ controlling invasive species on their properties, adding to the costs of production. Most weeds in Australia were, and still are,【C7】______introduced for agricultural or ornamental purposes. 【C8】______these plants have formed the basis of important industries and beautiful gardens, many have also gone on to become serious weeds — 70% of Australia's weeds are【C9】______garden plants that have "jumped the garden fence" . Some important commercial species, such as the radiata pine and the European olive, are also serious environmental weeds. More than 27,000 species of【C10】______ plants have been introduced to Australia since European colonization, with new species being introduced every year. About 10% of introduced species become naturalized in their new habitat, meaning they can【C11】______ their populations in the wild without human cultivation. One in ten naturalised plants become weeds, and have a negative【C12】______on native biodiversity, agriculture, or both. The price paid for species which become weeds is tremendous, both in economic and environmental【C13】______. Economically, weeds have been【C14】______to cost Australian agriculture a total of $ 4 billion every year: One in every seven dollars【C15】______farm income is spent on the control of weeds. The health costs of weeds are estimated at over a billion dollars annually, when medical treatment, drugs and time【C16】______work are added up — and money can't measure the human suffering caused by【C17】______health problems. Environmentally weeds have caused the【C18】______of four known species of Australian native plants, and 57 more are, or will soon become, threatened because of invasive introduced plants. Species like rubber vine in North Queensland have the potential to destroy entire native ecosystems【C19】______supplanting indigenous vine thickets, threatening native animals as well as plants. Vast areas of Australia and nearly every kind of native ecosystem【C20】______affected by introduced plants, from oceans and waterways to rainforests, grasslands and deserts.

单选题Many feminists attacked Hamlet"s exclamation: "______, thy name is woman!"

单选题The government"s recent statement of the unemployment does not______with the facts.

单选题He was shivering ______ cold. A. with B. on C. in D. by

单选题As a gifted writer, an ______ politician, a penetrating thinker, he stood far above the intellectual movement of which he become the leader.

单选题The new director made it clear that his staff were not to accept gifts from clients, ______.

单选题I am a ______ for the government. Every department is always asking for more money in their budgets.

单选题The economic stability of nations and continents is often affected by the abundance or ______ of natural resources.