单选题His leg was hurt. ______ is why he didnt come. A．It B．Which C．That D．There

单选题Billy Joel began taking piano lessons ______.

单选题Don't argue with him any longer. You are only wasting your breath ______ to win him over to your side.

单选题Even plants can run a fever, especially when they're under attack by insects or disease. But unlike humans, plants can have their temperature taken from 3,000 feet away——straight up. A decade ago, adapting the infrared (红外线) scanning technology developed for military purposes and other satellites, physicist Stephen Paley came up with a quick way to take the temperature of crops to determine which ones are under stress. The goal was to let farmers pre-cisely target pesticide (杀虫剂) spraying rather than rain poison on a whole field, which in- variably includes plants that don't have pest (害虫) problems. Even better, Paley's Remote Scanning Services Company could detect crop problems be- fore they became visible to the eye. Mounted on a plane flown at 3,000 feet at night, an infra- red scanner measured the heat emitted by crops. The data were transformed into a color-code map showing where plants were running" fevers". Farmers could then spot-spray, using 50 to 70 percent less pesticide than they otherwise would. The bad news is that Paley's company closed down in 1984, after only three years. Farmers resisted the new technology and long-term backers were hard to find. But with the renewed concern about pesticides on produce, and refinements in infrared scanning, Paley hopes to get back into operation. Agriculture experts have no doubt the technology works. "This technique can be used on 75 percent of agricultural land in the United States", says George Oerther of Texas A&M. Ray Jackson, who recently retired from the Department of Agricultrue, thinks re- mote infrared crop scanning could be adopted by the end of the decade. But only if Paley finds the financial backing which he failed to obtain 10 years ago.

单选题M: Christmas is round the corner and I'm looking for a gift for my girlfriend. Any suggestions?W: Well, you have to tell me something about your girlfriend first. Also, what's your budget?Q: What does the woman want the man to do? A. Plan his budget carefully. B. Give her more information. C. Ask someone else for advice. D. Buy a gift for his girlfriend.

单选题If there is one thing that could halt the ascent of social networks, it is the thorny question of privacy. This is (1) because it goes right to the (2) of the social-networking business model. In order to attract users, sites need to offer ways for members to restrict the information about themselves that gets shared with a wider (3) . But if a site allows members to keep too much of their information privacy, there will be less (4) that can be turned into profit through advertising and various other means, so the network's business will (5) . There is some evidence that people are starting to become more (6) about the way in which they (7) their data, which could have longer-term (8) for the networks' growth. Research published last year showed that some 60% of adults are restricting (9) to their online profiles. (10) , the social networks have partly brought this on themselves. In order to offer a better service, many have created (11) sets of privacy controls that allow users to switch between different levels of protection to (12) their online data. Facebook has excessive controls that can be adjusted to create different levels of (13) . Default settings for younger people on social-networking sites are often more (14) than those for adults to (15) they are protected from unwanted attention. Social networks (16) applause for developing these fine-grained controls. But their desire for profit can put them on a (17) course with privacy activists, regulators and their users. One bone of contention is social networks' (18) to draw attention to their privacy statements. The reason for this might be concern about "privacy reassurance": the worry that (19) people to privacy as a potential issue will make them less (20) to share things, even if robust privacy controls are available.

单选题The 33-year-old case has had more than ______.

单选题Whenever we planned our vacations, mother could always offer some ______ suggestions.

单选题Not only ______ us light, but also it gives us heat

单选题People from the South ______ very friendly.

单选题The opposite of adaptive divergence is an interesting and fairly common expression of evolution. Whereas related groups of organisms take on widely different characters in becoming adapted to unlike environments in the case of adaptive divergence. We find that Unrelated groups of organisms exhibit adaptive convergence when they spot similar modes of life or become suited for special sorts of environments. For example, invertebrate marine animals living firmly attached to the sea bottom or to some foreign object tend to develop a sub- cylindrical or conical form. This is illustrated by coral individuals, by many sponges, and even by the diminutive tubes of bryozoans. Adaptive convergence in taking this coral-like form is shown by some brachiopods and pelecypods that grew in fixed position. More readily appreciated is the streamlined fitness of most fishes for moving swiftly through water; they have no neck, the contour of the body is smoothly curved so as to give minimum resistance, and the chief propelling organ is a powerful tail fin. The fact that some fossil reptiles (ichthyosaurs) and modem mammals (whales, dolphins) are wholly fishlike in form is an expression of adaptive convergence, for these air-breathing reptiles and mammals, which are highly efficient swimmers, are not closely related to fishes. Unrelated or distantly related organisms that develop similarity of form are sometimes designated as homeomorphs (having same form).

单选题[此试题无题干]

单选题The author is in favor of the opinion that

单选题We felt ______ to death because we could make nothing of the lecturer's speech. A. exposed B. tired C. exhausted D. bored

单选题They also want the police"s use of force kept in check , especially in poor neighborhoods where everyone is apt to be treated like a suspect.