单选题Cell Phone Lets Your Secret Out Your cell phone holds secrets about you. Besides the names and (51) that you've programmed into it, traces of your DNA linger(逗留) on the device, according to a new study. DNA is genetic(遗传的) material that (52) in every cell. Like your fingerprint, your DNA is unique to you (53) you have an identical twin. Scientists today routinely analyze DNA in blood, saliva(涎，唾液), or hair left (54) at the scene of a crime. The results often help detectives identify (55) and their victims. Your cell phone can reveal more about you (56) you might think. Meghan J. McFadden, a scientist at McMaster University in Hamilton, Ontario, heard about a crime in which the suspect bled onto a cell phone and later dropped the (57) This made her wonder whether traces of DNA lingered on cell phones -- even when no blood was involved. (58) she and colleague Margaret Wallace of the City University of New York analyzed the flip-open phones(翻盖手机) of 10 volunteers. They used swabs(药签) to collect (59) traces of the users from two parts of the phone: the outside, where the user holds it, and the (60) , which is placed at the user's ear. The scientists scrubbed(用力擦洗；擦净) the phones using a solution made mostly (61) alcohol. The aim of washing was to remove all detectable traces of DNA. The owners got their phones (62) for another week. Then the researchers collected the phones and repeated the swabbing of each phone once more. The scientists discovered DNA that (63) to the phone's speaker on each of the phones. Better samples were collected from the outside of each phone, but those swabs also picked up DNA that belonged to other people who had apparently also handled the phone. (64) , DNA showed up even in swabs that were taken immediately after the phones were scrubbed. That suggests that washing won't remove all traces of evidence from a criminal's device. So cell phones can now be added to the (65) of clues that can clinch(确定，决定) a crime-scene investigation.

单选题Mary gets up at six o'clock every morning. A．rises B．stands C．arrives D．comes

单选题 The Natural Balance being Altered The balance of nature is a very elaborate and delicate system of check and countercheck. It is continually being altered as climates change, as new organisms evolve, as animals or plants spread to new areas. But the alterations have in the past, for the most part, been slow. whereas with the arrival of civilized man, their speed has been multiplied much: from the evolutionary time-scale, where change is measured by periods of ten or a hundred thousand years, they have been transferred to the human time-scale in which centuries and even decades count. Everywhere man is altering the balance of nature. He is facilitating the spread of plants and animals into new regions. Sometimes deliberately, sometimes unconsciously. He is covering huge areas with new kinds of plants, or with houses, factories, slagheaps and other products of his civilization. He gets rid of some species on a large scale, but favors the multiplication of others. In brief, he has done more in five thousand years to alter the biological aspect of the planet than has nature in five million years. Many of these changes which he has brought about have had unforeseen consequences. Who would have thought that the throwing away of a piece of Canadian waterweed would have caused half the waterways of Britain to be blocked for a decade? Or that provision of pot cacti for lonely settlers' wives would have led to Eastern Australia being covered with forests of prickly pears? Who would have predicted that the cutting down of forests on the Adriatic coast, or in parts of Central Africa, could have reduced the land to a semi-desert with the very soil washed away from the bare rock? Who would have thought that improved communications would have changed history by the spreading of disease-sleeping sickness into East Africa, measles into Ocean. AIDS around the whole world? These are spectacular examples, but examples on a smaller scale are everywhere to be found. We made a nature sanctuary for rare birds, providing absolute security for all species; and we may find that some common and hardy kind of birds multiplies beyond measure and drive away the rare kinds in which we are particularly interested. We see, owing to some little change brought about by civilization, the starting spread over the English countryside in hordes. We improve the yielding capacities of our cattle; and find that how they exhaust the pastures which were sufficient for less demanding stock. We gaily set about killing the carnivores that disturb our domestic animals, the hawks that eat our fowls and game-birds; and find that in so doing we are also removing the brake that restrains the multiplication of mice and other little rodents that gnaw away the farmers' profits.

单选题The minimum age of Chinese citizens who are eligible to vote is eighteen.A. encouragedB. enforcedC. entitledD. expected

单选题In the near future we can Ulook for/U more women in leadership roles.

单选题Night of the Living Ants When an ant dies, other ants move the dead insect out of the nest. This behavior is interesting to scientists, who wonder how ants know for sure and so soon that another ant is dead. Dong-Hwan Choe, a scientist at the University of California found that Argentine ants have a chemical on the outside of their bodies that signals to other ants. "I'm dead. Take me away." But there's a twist to Choe's discovery. These ants are a little bit like zombies (僵尸). Choe says that the living ants, not just the dead ones, have this death chemicals. In other words, while an ant crawls around, perhaps in a picnic or home, it's telling other ants that it's dead. What keeps ants from hauling away the living dead? Choe found that Argentine ants have two additional chemicals on their bodies, and these tell nearby ants something like, "Wait-I'm not dead yet." So Choe's research turned up two sets of chemical signals in ants: one says, "I'm dead," the other set says, "I'm not dead yet." Other scientists have tried to figure out how ants know when another ant is dead. If an ant is knocked unconscious, other ants leave it alone until it wakes up. That means ants know that unmoving ants can still be alive. Choe suspects that when an Argentine ant dies, the chemical that says "Wait-I'm not dead yet" quickly goes away. Once that chemical is gone, only the one that says "I'm dead" is left. "It's because the dead ant no longer smells like a living ant that it gets carried to the graveyard, not because its body releases new unique chemicals after death," said Choe. When other ants detect the "dead" chemical without the "not dead yet" chemical, they haul away the body. This was Choe's hypothesis (假设). To test his hypothesis, Choe and his team put different chemicals on Argentine ant pupae (蛹). When the scientists used the "I'm dead" chemical, other ants quickly hauled the treated pupae away. When the scientists used the "Wait-I'm not dead yet" chemicals, other ants left the treated pupae alone. Choe believes this behavior shows that the "not dead yet" chemicals override (优先于) the "dead" chemical when picked up by adult ants. And that when an ant dies, the "not dead yet" chemicals fade away. Other nearby ants then detect the remaining "dead" chemical and remove the body from the nest.

单选题Parents who lack the finance to send their children to a private school have to Utolerate/U the state system.

单选题Ms Hawkins handles the company's accounts. A. deals with B. deals in C. holds on D. holds out

单选题All the cars are tested for defects before leaving the factory.A. functionsB. faultsC. motionsD. parts

单选题He denies involvement with either drugs or the CIA.

单选题Although originally a German innovation, kindergarten got its real start in the United States as a movement to provide an improved learning environment for children.

单选题The plane will be taking off in {{U}}approximately{{/U}} 10 minutes.

单选题Cell Phone Lets Your Secret Out Your cell phone holds secrets about you. Besides the names and (51) that you've programmed into it, traces of your DNA linger on the device, according to a new study. DNA is genetic material that (52) in every cell. Like your fingerprint, your DNA is unique to you (53) you have an identical twin. Scientists today routinely analyze DNA in blood, saliva, or hair left (54) at the scene of a crime. The results often help detectives identify (55) and their victims. Your cell phone can reveal more about you (56) you might think. Meghan J. McFadden, a scientist at McMaster University in Hamilton, Ontario, heard about a crime in which the suspect bled onto a cell phone and later dropped the (57) . This made her wonder whether traces of DNA lingered on cell phones even when no blood was involved. (58) she and colleague Margaret Wallace of the City University of New York analyzed the flip-open phones of 10 volunteers. They used swabs to collect (59) traces of the users from two parts of the phone: the outside, where the user holds it, and the (60) , which is placed at the user's ear. The scientists scrubbed the phones using a solution made mostly (61) alcohol. The aim of washing was to remove all detectable traces of DNA. The owners got their phones (62) for another week. Then the researchers collected the phones and repeated the swabbing of each phone once more. The scientists discovered DNA that (63) to the phone's speaker on each of the phones. Better samples were collected from the outside of each phone, but those swabs also picked up DNA that belonged to other people who had apparently also handled the phone. (64) , DNA showed up even in swabs that were taken immediately after the phones were scrubbed. That suggests that washing won't remove all traces of evidence from a criminal's device. So cell phones can now be added to the (65) of clues that can clinch a crime-scene investigation.

单选题She answered the difficult question, which was an {{U}}immense{{/U}} load off her heart. A. natural B. fatal C. tiny D. enormous

单选题第三篇 Electronic Teaching The potential of closed-circuit television and other new electronic teaching tools is so great that it is fascinating to visualize "the school of tomorrow". Televised lessons will originate from a central building having perhaps four or five master studios. The lessons will be carried into classrooms all over a city, or even an entire country. After a televised lesson has been given, the classroom teacher will take over for the all-important "follow-up" period. The students will ask any troublesome questions, and difficult points will be cleared up through discussion. The teacher in the classroom will have additional electronic tools. On the teacher"s desk, the traditional chalk and erasers will have been replaced by a multiple-control panel and magnetic tape player. The tape machines will run pre-recorded lessons which pupils will follow by headphones. The lessons will be specifically geared to the students" levels of ability. For instance, while the class as a whole studies history, each student will receive an individual history lesson, directed to his particular level of ability. Should question arise, the students will be able to talk directly to the teacher on individual "intercoms" without disturbing the rest of the class. In this way, the teacher will be able to conduct as many as three classes at the same time. With the rapid development of computer science, students will be aided with specially prepared multimedia software to study their subjects better. Homework will possibly be assigned and handed in via electronic mail system. Students can even take examinations on their computer linked with the teacher"s and get the score instantly. They will get certificates or diplomas if they pass all the required examinations. Experts believe that this type of education will be very popular in the years ahead.

单选题His shoes were shined to perfection.A. clearedB. washedC. polishedD. mended

单选题 Crystal Ear One day a friend asked my wife Jill if I wanted a hearing aid. "He certainly does," replied Jill. After hearing about a remarkable new product, Jill finally got up the nerve to ask me if I'd ever thought about getting a hearing aid. "No way," I said. "It would make me look 20 years older." "No, no," she replied. "This is entirely different. It's Crystal Ear!" Jill was right. Crystal Ear is different--not the old-styled body worn or over-the-ear aid, but an advanced personal sound system so small that it's like contacts (隐形眼镜) for your ears. And Crystal Ear is super-sensitive and powerful, too. You will hear sounds your ears have been missing for years. Crystal Ear will make speech louder, and the sound is pure and natural. I couldn't believe how tiny it is. It is smaller than the tip of my little finger and it's almost invisible when worn. There are no wires, no behind-the-ear device. Put it in your ear and it’s ready-to-wear mold (形状) fits comfortably. Since it's not too loud or too tight, you may even forget that you're wearing it! Use it at work or at play. And if your hearing problem is worse in certain situations, use Crystal Ear only when you need it. Hearing loss, which occurs typically prior to teenage years, progresses throughout one's lifetime. Although hearing loss is now the world's number one health problem, nearly 90 percent of people suffering hearing loss choose to leave the problem untreated. For many millions, treating hearing loss in a conventional way can involve numerous office visits, expensive testing and adjustments to fit your ear. Thanks to Crystal Ear, the "sound solution" is now convenient. Almost 90 percent of people with mild hearing loss, and millions more with just a little hearing drop-off (下降), can be dramatically helped with Crystal Ear. Moreover, its superior design is energy-efficient, so batteries can last months. Crystal Ear is now available to help these people treat their hearing loss with a small hearing amplifier (放大器).

单选题Whatever the world's governments decide to do about climate change, one thing seems certain: the value of carbon is going to rise. Government and industry are beginning to invest in technologies to capture carbon from their smokestacks (大烟囱),and entrepreneurs are beginning to figure out ways to recycle it. One of them is Carbon Sciences, a Santa Barbara, California, firm that says it has found an efficient way of turning carbon dioxide and water into methanol, a type of fuel that racing cars now use instead of gasoline. (Although the fuel would produce carbon when it's burned, its net effect would be neutral, says the company, because carbon was used in producing it.) What is methanol according to the passage?A. It is a kind of waste that cars emit.B. It is a kind of naturally-produced fuel.C. It is a kind of fuel that racing cars use.D. It is a kind of fuel from smokestacks.

单选题For young children, getting dressed is a complicated business.A. strangeB. complexC. personalD. funny

单选题Forester stared at his car, trembling with rage.A. turningB. jumpingC. shakingD. shouting