练习册

  • 练习册
  • 试题
    The fiddler crab (蟹) is a living clock. It indicates the time of day by the colour of its skin, which is dark by day and pale by night. The crab’s changing colour follows a regular twenty-four hour plan that exactly matches the daily rhythm of the sun. Does the crab actually keep time, or does its skin simply answer to the sun’s rays, changing colour according to the amount of light strikes it? To find out, biologists kept crabs in a dark room for two months. Even without daylight, the crab’s skin colour continued to change exactly on time. This characteristic probably developed gradually in answer to the daily rising and setting of the sun, to help protect the crab from sunlight and enemies. After millions of years it has become completely regulated inside the living body of the crab. The biologists noticed that once each day the colour of the fiddler crab is especially dark, and that each day this happens fifty minutes later than on the day before. From this they discovered that each crab follows not only the rhythm of the sun but also that of the tides . The crab’s period of greatest darkening is exactly the time of low tide on the beach where it was cought! 【查看更多】

     

    题目列表(包括答案和解析)

    听力(共2节，每小题1分，满分20分)

    第一节　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。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。

    1．When will the plane take off?

    A．At 5∶15．

    B．At 5∶30．

    C．At 5∶00．

    2．What does the man want to do?

    A．He wants to know where the computers are．

    B．He wants to sell computer disks．

    C．He wants to buy computer disks．

    3．What are they going to do?

    A．To see an exhibition．

    B．To have a meeting．

    C．To listen to a lecture．

    4．How much does the pen cost?

    A．13 yuan．

    B．27 yuan．

    C．7 yuan．

    5．Why is the man late?

    A．He could not walk fast．

    B．He failed to catch his bus again．

    C．His clock stopped．

    第二节　听下面5段对话或独白。每段对话或独白后有几个小题，从题中所给的A，B，C三个选项中选出最佳选项。听每段对话或独白前，你将有时间阅读各个小题，每小题5秒钟；听完后，每小题将给出5秒钟的作答时间。每段对话或独白读两遍。

    听第6段材料，回答第6至7题。

    6．For whom does the woman probably want to buy a ski jacket?

    A．For her husband．

    B．For her son．

    C．For her daughter．

    7．Why doesn’t the woman buy the jacket?

    A．It’s too expensive．

    B．It’s too big．

    C．She doesn’t like the colors．

    听第7段材料，回答第8至9题。

    8．What do they know about Bob’s illness?

    A．He must have got it in India．

    B．He must have worked too hard．

    C．He must have been badly treated when ill in India．

    9．What is NOT true about his illness?

    A．He is getting better and better．

    B．He should have seen a doctor earlier．

    C．It was too late to send him to the hospital．

    听第8段材料，回答第10至12题。

    10．Where does the conversation probably take place?

    A．In a bookstore．

    B．In a department store．

    C．In a ticket office．

    11．Does the man find what he wants?

    A．Yes．

    B．No．

    C．He’s still looking for it．

    12．Which of the following is not true when the man wants that thing?

    A．It is sold out．

    B．The man can come back for it after some days．

    C．They don’t sell this here．

    听第10段材料，回答第13至16题。

    13．What does the boy want to celebrate?

    A．His 18th birthday．

    B．His 19 th birthday．

    C．His 20th birthday．

    14．Where does the boy want to celebrate his birthday?

    A．In a bar．

    B．At his home．

    C．In a restaurant．

    15．What does the woman suggest?

    A．Making a salad．

    B．Buying some flowers．

    C．Buying some drinks．

    16．When will the boy order a birthday cake?

    A．On Saturday morning．

    B．On Saturday afternoon．

    C．On Sunday morning．

    听第9段材料，回答第17至20题。

    17．Who is the speaker?

    A．An official．

    B．A tourist．

    C．A guide．

    18．When can you come if you want to see how bread was baked 200 years ago?

    A．On Sunday afternoon．

    B．On Tuesday morning．

    C．On Saturday afternoon．

    19．Where did Sir Henry come from?

    A．England．

    B．The USA．

    C．France．

    20．How many interesting places are mentioned here?

    A．Two．

    B．Three．

    C．Four．

    查看答案和解析>>


    同步练习册答案