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    Wind is the great maker of waves. There are exceptions, such as the tidal（潮汐的）waves sometimes produced by earthquakes under the sea. But the waves most of us know are produced by winds blowing over the sea.
    

    Now before constructing an imaginary life history of a typical wave, we need to know certain physical things about it. Awave has height, from trough（low point）to crest （high point）. It has length-the distance from this crest to that of the following wave. The period of the wave means the time it takes for succeeding crests to pass a fixed point. None of these things stays the same-for all depend upon the wind, upon the depth of the water and many other matters.
    

    The water that makes up a wave does not advance with it across the sea. Each drop of water turns around in a little circle with the passing of the wave, but returns very nearly to its original position. And it is fortunate that this is so. For if the huge masses of water that make up a wave actually moved across the sea, sailing would be impossible.
    

    If we want to find the speed of a wave, we may use the following way：
    

    Speed=wavelengthfrequency
    

    Here, wavelength is the distance between two high points（crests）, frequency means the number of cycles per second.
    

70. What causes waves?
    

  A. Earthquakes and nothing else.        B. Only wind.
    

    C. Wind causes most waves.                D. Wind causes some waves.
    

  71. Which of the following is true according to the passage?
    

    A. The water of a wave moves away across the sea.
    

    B. The water of a wave remains almost at the same place.
    

    C. The waster of a wave goes with the passing of the ware.
    

    D. The length of a wave means the distance from the top of a wave to the bottom.
    

  72. The speed of Wave 1 is100cm/s, frequency 10. The frequency of Wave 2 is 300, while its speed is twice that of Wave 1. Which of the following is right?
    

    A. The wavelength of the two is equal.
    

    B. The wavelength of Wave 1 is 10 times longer than that of Wave 2.
    

    C. The wavelength of Wave 2 is longer than that of Wave 1.
    

    D. The wavelength of Wave 1 is longer than that of Wave 2.
    

D
    

    Readingto dogs is an unusual way to help children improve their literacy skills. With their shining brown eyes, wagging tails, and unconditional love, dogs can provide the nonjudgmental listeners needed for a beginning reader to gain confidence, according to Intermountain Therapy Animals （ITA） in Salt Lake City. The group says it is the first program in the country to use dogs to help develop literacy in children, with the introduction of Reading Edueation Assistance Dogs（READ）.
    

    The Salt Lake City Public Library is sold on the idea. “Literacy specialists admit that children who read below the level of their fellow pupils are often afraid of reading aloud in a group, often have lower self-respect, and regard reading as a headache,” said Lisa Myron, manager of the children’s department.
    

    Last November, the two groups started “Dog Day Afternoon” in the children's department of the main library. About 25 children attended each of the four Saturday-afternoon classes, reading for half an hour. Those who attended three of the four classes received a “pawgraphed” book at the last class.
    

    The program was so successful that the library plans to repeat it in April, according to Dana Thumpowsky, public relations manager.
    

73. What is mainly discussed in the text?
    

    A. Children’s reading difficulties.   B. Advantages of raising dogs.
    

    C. Service in public library        D. A special reading program.
    

74. Specialists use dogs to listen to children reading because they think ______________.
    

    A. dogs are young children's best friends
    

    B. children can play with dogs while reading
    

    C. dogs can provide encouragement for shy children
    

    D. children and dogs understand each other
    

75. By saying “The Salt Lake City Public Library is sold on the idea”, the writer means the library ____________.
    

    A. uses dogs to attract children
    

    B, accepts the idea put forward by ITA
    

    C. has opened a children's department
    

    D. has decided to train some dogs
    

76. A “pawgraphed” book is most probably_____________.
    

    A. a book used in Saturday classes      B. a book written by the children
    

    C. a prize for the children             D. a gift from parents
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