单选题Listen to that laughter! They ______ themselves.

单选题To fight against computer crimes, a computer system needs a sure way of identifying its right users and rejecting those who are not entitled to use it. The identification system should be quick, simple, and convenient. At present, signatures are widely used to identify credit card holders, but it takes an expert to detect a good forgery. Sometimes even a human expert is fooled, and there is no reason to believe that a computer could do any better. Photographs are also sometimes used for identification. But, people find it inconvenient to stop by a credit card company aid to be photographed. Companies might lose business if they made the pictures under absolute requirement. Also, photographs are less useful these days, when people frequently change their appearance by changing the way they wear their hair. Finally, computer programs for analyzing photographs are still highly experimental. Cash-drawing systems often use two identification numbers: One is recorded on a magnetic stripe on the identification cards, and the other is given to the CRS holder. When the user inserts his card into the cash-drawing terminal, he keys in the identification number he has been given. The computer checks to see that the number recorded on the card and the other keyed in by the user refer to the, same person. For a long time, fingerprints have provided a method of positive identification. But they suffer from two problems. One is that there is no simple system for comparing fingerprints electronically, the other is that because most people associate being fingerprinted with being arrested; they almost surely would resist being fingerprinted for routine identification. Voiceprints have been suggested. With these, the user has only to speak a few words for the computer to analyze his voice. There are no psychological problems here. And technically it"s easier to take and analyze voiceprints than fingerprints. However, it has yet to be proved that the computer cannot be fooled by imitation. Also, the voice is subjected to the noise and distortion of a telephone line. Even lipprints have been suggested. But it"s doubtful that kissing computers will ever catch on.

单选题There Was nothing we could do ______ wait.

单选题The word "parochial" in the last paragraph means ______.

单选题 The president is ill, so the secretary will be ______ for him as chairman at the meeting.

单选题We're moving to a more ______ neighborhood.

单选题Five score years ago, a great American, ______ symbolic shadow we stand, signed the Emancipation Proclamation.

单选题The reason that the Coloured Resistance Movement didn't succeed is that ______.

单选题I'd rather you______so rudely to her.

单选题The history of Western music properly begins with the music of the Christian Church. But all through the Middle Ages and even to the present time men have continually turned back to Greece and Rome for instruction, for correction, and for inspiration in the several fields of work; this has been true in music, though with some important differences. Roman literature, for example, never ceased to exert influence in the Middle Ages, and this influence became much greater in the fourteenth and fifteenth centuries when more Roman works became known; at the same time, too, the surviving literature of Greece was gradually recovered. But in literature, as well as in some other fields (notably sculpture), medieval or Renaissance artists had the advantage of being able to study and, if riley so desired, imitate the models of antiquity. The actual poems or statues were before them. In music this was not so. The Middle Ages did not possess a single example of Greek or Ro man music--nor, it may be added, are we today much better off. About a dozen examples--half of them were fragments of Greek music have been discovered, nearly all from comparatively late periods, but there is no general agreement as to just how they were meant to sound; there are no authentic remains of ancient Roman music. So we, as well as the men of medieval times, derive nearly all our knowledge of this an in the ancient civilizations at second hand from a few rather vague accounts of performances, but mostly from theatrical treatises and literary descriptions.

单选题The______in our soaps should come only from essential oils, which are steamed or pressed from plants.

单选题What does the writer think about the creation of new desert areas?

单选题Despite the fact that they were ______ when they married, after 30 years they live together harmoniously.

单选题Educators are now recommending that reasoning skills ______ in the class room since recent tests indicate that many teachers in the past have ignored these skills.

单选题The author regards the idea that differentiation is triggered randomly when paired claws remain intact as ______.

单选题The phrase "paring them down" in the third paragraph most likely means ______.

单选题These pollutants can be ______ hundreds and eve thousands of kilometers by large air masses.(2003年中国科学院考博试题)

单选题He used to play badminton with you, ______ ?