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以下有四种说法：

①“a>b”是“a2>b2”的充要条件；

②“A∩B＝B”是“B＝∅”的必要不充分条件；

③“x＝3”的必要不充分条件是“x2－2x－3＝0”；

④“m是实数”的充分不必要条件是“m是有理数”．

其中正确说法的序号是________．

答案

②③④

如2>－4，但22<(－4)2，故①错；②正确；x＝3可推出x2－2x－3＝0成立，反之则不一定成立，所以③正确；“m是有理数”可以推出“m是实数”，反之不一定成立，所以④也正确．

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任务型阅读。
     下面是四位同学写给《Learning English》编辑Dick的求助信。在信中，四位同学分别谈了自己在学习和生活中的问题。
     A. 请将四封信与问题进行配对，并把序号A、B、C、D填入1-4  题题后相应的横线上。
A.       
Dear Editor ,
      I am a student from a junior middle school. I am good at all subjects except English. I can’t remember words well. I am especially weak in speaking and listening. What shall I do?
                                                                                                                              John
B.
Dear Editor ,
      I have a problem! I really don’t know what to say when I meet strangers . I find it hard to
talk with others because I’m afraid they might laugh at me. I am not as clever or funny as my
friends. If people start talking to me, they will realize that I am just boring. Please help me.
                                                                                                                                Lily 
 
C.
Dear Editor,
      I was getting on well with my best friends. But a few days ago, another friend of mine told me that she often said bad words about me. When I heard this, I was very angry. What should I do? Should I stop being her friend or stay with her as usual?
                                                                                                                              Betty
D.
Dear Editor,
      Recently I have much difficulty in falling asleep. When I go to bed, I feel very sleepy, but I
always think a lot and can’t fall asleep. So I always feel very tired in class and sometimes my
head hurts badly. Could you give me some advice?
                                                                                                                           Steven
1.The student finds it difficult to fall asleep.    _______
2.The student doesn’t know what to say to strangers.    _______
3.The student doesn’t know how to learn English well.   _______
4.The student doesn’t know if she should still stay with her best friend.    _______
B. 假如你是编辑Dick，请针对Steven同学的问题，给他提出一条合理性的建议。(用一句话表达)
5._______________________________________________________
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单项选择题 A1/A2型题

与原发性肝癌比较，下列哪项对诊断肝转移癌最有价值（）

A.边界清楚

B.多发病灶，伴"牛眼征"

C.环样强化

D.延迟扫描为低密度灶

E.动脉期明显强化
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