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9.Why is the man interested in such news?

    A.Because he hopes to go to the moon.

    B.Because he is an astronaut.

    C.Because he wants to do research in space.

听第8段材料,回答第10至12题。

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8.What was the news about?

    A.It’s about the space station.

    B.It’s about the space.

    C.It’s about the astronauts.

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7.Why does the woman think New York is a nice place to live?

    A.It has a large population.

    B.It offers an exciting life.

    C.It’s interesting and quiet.

听第7段材料,回答第8至9题。

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6.Where does the man probably live?

    A.In the countryside.  B.In a big city.       C.In America.

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4.What conclusion can we draw from the conversation?

    A.John had been working hard.

    B.John probably didn’t work hard.

    C.The woman was sorry to hear the news.

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3.What did the woman buy for her husband?

    A.A stamp.          B.A watch.          C.A toy

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2.What does the woman want to buy?

    A.Cameras.         B.Pictures.          C.Films.

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1.Where are the two speakers?

    A.In a restaurant.     B.In a hotel.         C.In the street.

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35.(10分)红薯和土豆都富含淀粉,但红薯吃起来比土豆甜。为探究其原因,某兴趣小组在不同温度、其它条件相同的情况下对处于休眠期的红薯块根与土豆块茎处理30分钟后测定还原糖的含量。结果如图:

  (1)由图中曲线可知,60°C时红薯还原糖含量最高,原因     

  (2)土豆不含还原糖的原因是           

  (3)为了确定土豆不含淀粉的原因,请完成以下实验:

实验原理:①淀粉能被淀粉酶水解为还原糖;

                  

备选材料与用具:去掉淀粉与还原糖的红薯提取液,去掉淀粉的土豆提取液,双缩脲试剂A液,双缩脲试剂B液,斐林试剂A液,斐林试剂B液,苏丹红染液,3%淀粉溶液,3%蔗糖溶液等。

实验步骤:

第一步:取A、B两支试管,在A试管中加入去掉淀粉的土豆提取液2 ml,在B试管中加入去掉淀粉与还原糖的红薯提取液2 ml   水浴保温5分钟。

第二步:向A、B两试管中加入等量的水浴加温至60°C的     溶液。水浴保温5分钟。

第三步:将             后,向A、B试管内各加入2 ml。然后,          

最可能的实验结果:             

  (4)食用土豆时,消化分解成的葡萄糖,几乎被小肠上皮细胞全部吸收,该吸收过程需要       。糖尿病人食用较多土豆,吸收的葡萄糖不同于常人的代谢出路是        

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