单选题Electronic mail has become an extremely important and popular means of communication. The convenience and efficiency of electronic mail are threatened by the extremely rapid growth in the volume of unsolicited commercial electronic mail. Unsolicited commercial electronic mail is currently estimated to account for over half of all electronic mail traffic, up from an estimated 7 percent in 2001, and the volume continues to rise. Most of these messages are fraudulent or deceptive in one or more respects. The receipt of unsolicited commercial electronic mail may result in costs to recipients who cannot refuse to accept such mail and who incur costs for the storage of such mail, or for the time spent accessing, reviewing, and discarding such mail, or for both. The receipt of a large number of unwanted messages also decreases the convenience of electronic mail and creates a risk that wanted electronic mail messages, both commercial and noncommercial, will be lost, overlooked, or discarded amidst the larger volume of unwanted messages, thus reducing the reliability and usefulness of electronic mail to the recipient. Some commercial electronic mail contains material that many recipients may consider vulgar or pornographic in nature. The growth in unsolicited commercial electronic mail imposes significant monetary costs on providers of Internet access services, businesses, and educational and nonprofit institutions that carry and receive such mail, as there is a finite volume of mail that such providers, businesses, and institutions can handle without further investment in infrastructure. Many senders of unsolicited commercial electronic mail purposefully disguise the source of such mail. Many senders of unsolicited commercial electronic mail purposefully include misleading information in the messages' subject lines in order to induce the recipients to view the messages. While some senders of commercial electronic mail messages provide simple and reliable ways for recipients to reject (or "opt-out" of) receipt of commercial electronic mail from such senders in the future, other senders provide no such "opt-out" mechanism, or refuse to honor the requests of recipients not to receive electronic mail from such senders in the future, or both. Many senders of bulk unsolicited commercial electronic mail use computer programs to gather large numbers of electronic mail addresses on an automated basis from Internet websites or online services where users must post their addresses in order to make full use of the website or service. The problems associated with the rapid growth and abuse of unsolicited commercial electronic mail cannot be solved by the government alone. The development and adoption of technological approaches and the pursuit of cooperative efforts with other countries will be necessary as well.

单选题There has been enough playing around, so let's get down to business.

单选题When people have no will to live, people are often very difficult to help. A. you are B. they are C. it is D. the other is

单选题The guest team was beaten by the host team 2 ______ 4 in last year's CFA Cup Final.

单选题Walking through my train yesterday, staggering from my seat to the buffet and back, I counted five people reading Harry Potter novels. Not children—these were real grown-ups reading children"s books. It was as if I had wandered into a John wyndham scenario where the adults" brains have been addled by a plague and they have returned to childishness, avidly hunting out their toys and colovring—in books. Maybe that would have been understandable. If these people had jumped whole-heartedly into a second childhood it would have made more sense. But they were card-carrying grown-ups with laptops and spreadsheets returning from sales meetings and seminars. Yet they chose to read a children"s book. I don"t imagine you"ll find this headcount exceptional. You can no longer get on the London Tube and not see a Harry Potter book. Nor is it just the film; these throwback readers were out there in droves long before the movie campaign opened. So who are these adult readers who have made JK Rowling the second-biggest female earner in Britain (after Madonna)? As I have tramped along streets knee-deep in Harry Potter paperbacks , I"ve mentally slotted them into three groups. First come the Never-Readers, whom Harry has enticed into opening a book. Is this a bad thing? Probably not. Writing has many advantages over film, but it can never compete with its magnetic punch. If these books can re-establish the novel as a thrilling experience for some people, then this can only be for the better. If it takes obsession-level hype to lure them into a bookshop. That"s fine by me. But will they go on to read anything else? Again, we can only hope. The second group are the Occasional Readers. These people claim that tiredness, work and children allow them to read only a few books a year. Yet now-to be part of the crowd, to say they"ve read it—they put Harry Potter on their oh-so-select reading list. It"s infuriating , and maddening. Yes, I"m a writer myself, currently writing difficult, unreadable, hopefully unsettling novels, but there are so many other good books out there, so much rewarding, enlightening, enlarging works of fiction for adults; and yet these sad cases are swept along by the hype, the faddism, into reading a children"s book. The third group are the Regular Readers, for whom Harry is sandwiched between McEwan (英国 当代作家) and Balzac, Roth (德国现代诗人) and Dickens. This is the real baffler—what on earth do they get out of reading it? Why bother? But if they call rattle through it in a week just to say they"ve been there—like going to Longleat (朗利特山庄英国名胜) or the Eiffel Tower—the worst they"re doing is encouraging others.

单选题Besides their sharing traditional male roles, women also play roles entirely different from those ______ by men.

单选题 The question of what children learn and how they should learn it is continually being debated and redebated. Nobody dares any longer to defend the old system, the learning of lessons parrot-fashion and the grammar with-a-whip system, which was good enough for our grandparents. The theorists of modem psychology have stepped in to argue that we must understand the needs of children. Children are not just small adults; they are children who must be respected as such. Well, you may say, this is as it should be, and a good idea. But think further. What happens? "Education" becomes the responsibility not of teachers, but of psychologists. What happens then? Teachers worry too much about the psychological implications of their lessons, and forget about the subjects themselves. If a child dislikes a lesson, the teacher feels that it is his fault, not the child's. So teachers worry whether history is "relevant" to modem young children. And do they dare to recount stories about violent battles? Or will this make the children themselves violent? Can they tell their classes about children of different races, or will this encourage racial hatred? Why teach children to write grammatical sentences? Verbal expression is better. Sums? Arithmetic? No, no; real-life mathematical situations are more understandable. You see you can go too far. Influenced by educational theorists, who have nothing better to do than write books about their ideas, teachers leave their teacher-training colleges filled with grand, psychological ideas about children and their needs. They make elaborate, sophisticated preparations and try out their "modem methods" on the long-suffering children. Since one "modem method" rapidly replaces another, the poor kids will have had a good bellyful by the time they leave school. Frequently the modem methods are so sophisticated that they fail to be understood by the teachers, let alone the children; even more often, the relaxed discipline, so essential for the "informal" feeling the class must have, prevents all but a handful of children from learning anything.

单选题It must comply strictly Uin/U safety standards to be accepted by the public, and at the same time it must demonstrate that no health or environmental damage occurs.

单选题As the Olympic flame was ______ and the flags lowered, the closing ceremony concluded with a firework display.

单选题She told me that she has already gone to the United States four times before she attended that conference.

单选题Alaskans love reading books about

单选题About fifty years ago, plant physiologists set out to grow roots by themselves in solutions in laboratory flasks. The scientists found that the nutrition of isolated roots was quite simple. They required sugar and the usual minerals and vitamins. However, they did not require organic nitrogen compounds. These roots got along free on mineral inorganic nitrogen. Roots are capable of making their own proteins and other organic compounds. These activities by roots require energy, of course. The process of respiration uses sugar to make the high energy compound ATP, which drives the biochemical reactions. Respiration also requires oxygen. Highly active roots require a good deal of oxygen. The study of isolated roots has provided an understanding of the relationship between shoots and roots in intact plants. The leaves of the shoots provide the roots with sugar and vitamins, and the roots provide the shoots with water and minerals. In addition, roots can provide the shoots with organic nitrogen compounds. This comes in handy for the growth of buds in the early spring when leaves are not yet functioning. Once leaves begin photosynthesizing, they produce protein, but only mature leaves can "export" protein to the rest of the plant in the form of amino acids.

单选题Hydroponics ______ the cultivation of plants without soil.

单选题All workers, regardless of their sex and education, are required to ______ at the age of 60.

单选题The eastern bluebird is considered the most attractive bird native of North America by many bird-watchers.

单选题I will go home for the vacation as soon as I have finished my exams.

单选题The girl made a light of her disappointment at being too sick to go to the dance.

单选题The fun of playing the game was a greater incentive than the prize.

单选题This passage, on the whole, is developed by ______

单选题The doctor said that the patient had______at once.