单选题Learning how to fly took nature millions of years of trial and error—but a winged robot has crackedit in only a few hours, using the same evolutionary principles. Krister Wolff and Peter Nordin of Chalmers University of Technology (CUT) in Gothenburg, Sweden, built a winged robot and set about testing whether it could learn to fly by itself, without any pre-programmed data on what flapping is or how to do it. To begin with, the robot just twitched and jerked erratically. But, gradually, it made movements that gained height. At first, it cheated—simply standing on its wing tips was one early short cut. After three hours, however, the robot abandoned such methods in favor of a more effective flapping technique where it rotated its wings through 90 degrees and raised them before twisting them back to the horizontal and pushing down. "This tells us that this kind of evolution is capable of coming up with flying motion," says Peter Bentley, who works on evolutionary computing at University College London. But while the robot had worked out how best to produce lift, it was not about to take off. "There's only so much that evolution can do," Bentley says. "This thing is never going to fly because the motors will never have the strength to do it," he says. The robot had metre-long wings made from balsa wood and covered with a light plastic film. Small motors on the robot let it move its wings forwards or backwards, up or down or twist them in either direction. The team attached the robot to two vertical rods, so it could slide up and down. At the start of a test, the robot was suspended by an elastic band. A movement detector measured how much lift, if any, the robot produced for any given movement. A computer program fed the robot random instructions, at the rate of 20 per second, to test its flapping abilities. Each instruction told the robot either to do nothing or to move the wings slightly in various directions. Feedback from the movement detector let the program work out which sets of instructions were best at producing lift. The most successful ones were paired up and "offspring" sets of instructions were generated by swapping instructions randomly between successful pairs. These next-generation instructions were then sent to the robot and evaluated before breeding a new generation, and the process was repeated.

单选题Readers ______ can very smoothly without knowing the exact meaning of each word.

单选题Scottish soldiers wore kilts partly because of _______.

单选题 阅读下列短文，从每题所给的四个选项(A、B、C和D)中，选出最佳选项。{{B}}A{{/B}} Stage plays, at first, seem a lot like films. Both use actors and dialogue and scenery. But if you try to make a film by setting up a camera in front of the stage, you will find it won't work. A film made in this way will leave the audience cold. And even worse you'll be wasting a powerful tool—the camera. A stage is actually a box. One side of the box has been removed so the audience can see what's going on inside. The actors remain at a fixed audience. In the film, however, the camera can bring the audience up close and fix their attention on small but important things: a frightened look, a whisper, a trembling of hands. The camera offers the film maker freedom allowing him to move easily across barriers (界 限) of time and space. He can show his action in real cities and on real farms. He can also use the camera to change the scene dozens of times in one film. No expert of the stage can do this.

单选题{{B}}C{{/B}} WASHINGTON -- considering the serious warnings lately about Internet viruses(病毒), users may don't use their machines just to keep them safe. In reality, common sense and a few basic tips can keep Internet surfers secure. Anti-virus software is a must, and it should be updated at least once a week to recognize newly viruses. If this is not done, you will meet great troubles. People with broadband Internet connections should have also a firewall. These protect the computer from attacks by hackers(黑客). Then it is time to think about computer habits. Unlike old viruses, which spread only through shared disks, the Internet brings viruses straight to the e-mail box. ff an e-mail with attachment(附件) comes from an unknown sender, or unexpectedly from a known' sender, it should not be opened. On receiving an unexpected attachment from a friend, experts suggest a telephone call to make sure of the mail' s source before opening. If you open the mail without any consideration, you will be easily attacked by the hackers.

单选题How about the two of us ______ a walk down the garden?

单选题______ you go, you should bear the motherland in mind. A.Where B.Whenever C.However D.Wherever

单选题听下面5段对话。每段对话后有一个小题，从题中所给的A、B、C三个选项中选出最佳选项，并标在试卷的相应位置。听完每段对话后，你都有10秒钟的时间来回答有关小题和阅读下一小题。每段对话仅读一遍。

单选题Ralph and Celia ______ a lot of each other since they moved to the same city.

单选题The United States is a federal union of 50 states. The capital of national government is in Washington, D. C. (District of Columbia). The Federal Constitution sets up the structures of the national government and lists its powers and activities. The constitution gives Congress the authority to make laws which are necessary for the common defense and the good of the nation. It also gives the Federal Government the power to deal with national and international problems that involve more than one state. All powers that are not given to the Federal Government by the constitution are the responsibility of the individual states. The Federal Government has three branches—the executive, the legislative, and the judicial. The legislative branch makes the laws, executive branch carries out the laws, and judicial branch interprets the laws. The President heads the executive branch and the Supreme Court heads the judicial branch. The legislative branch includes both houses of Congress—the Senate and the House of Representatives. The constitution limits the powers of each branch and prevents one branch from gaining too much power. For example, Congress can pass a law and the President may sign it. Nevertheless, the Supreme Court can declare the law unconstitutional and nullify it. All government in the United States is "of the people, by the people and for the people". The people elect the President and the members of Congress. However, the President appoints the heads of federal departments and the Supreme Court judges. Every citizen votes in secret. Consequently, no one knows for whom an individual votes. The people believe that their government should provide a frame word and order within which they are left free to run their own lives.

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单选题—Did you enjoy last night's concert? —Yes. Though the last piece ______ rather poorly.A. was playingB. playedC. was playedD. playing

单选题—Can you come on Monday or Tuesday? —I'm afraid ______ day is possible. A. any B. some C. neither D. either

单选题The British arc not so familiar with different cultures and other ways of doing things,______ is often the case in other countries.

单选题It was dark. We decide to ______ for the night at a farmhouse.[A] put away[B] put down[C] put up[D] put on

单选题I finally got the job I dreamed about. Never in all my life ______ so happy. A.did I feel B.I felt C.I had felt D.had I felt