矩形的两条对角线把这个矩形分成了四个______三角形．菱形的两条_爱下问搜题

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问题填空题

矩形的两条对角线把这个矩形分成了四个______三角形．菱形的两条对角线把这个菱形分成了四个______三角形．正方形的两条对角线把这个正方形分成了四个______三角形．

答案

证明：（1）矩形的对角线相等且互相平分，所以矩形的对角线把矩形分成了四个等腰三角形；

（2）菱形的对角线互相垂直，所以菱形的两条对角线把这个菱形分成了四个直角三角形；

（3）正方形的对角线互相垂直且平分且相等，故正方形的两条对角线把这个正方形分成了四个等腰直角三角形．

完形填空

Coming home from school that dark winter day so long ago, I was filled with excitement of having the weekend off. But I was 41 into stillness by what I saw. Mother, seated at the far end of the sofa, was 42 with the second-hand green typewriter on the table. She told me that she couldn’t 43 fast and then she was out of work. My shock and embarrassment at finding Mother in tears was a perfect proof of how 44 I understood the pressure on her. Sitting beside her on the sofa, I began very slowly to understand. “I guess we all have to 45 something,” Mother said quietly. I could 46 her pain and the tension of 47 the strong feeling that were interrupted by my 48 . Suddenly, something inside me lit up. I reached out and put my arms around her. She broke then. She put her face 49 my shoulder and sobbed. I held her 50 and didn’t try to talk. I knew I was doing what I should, what I could and that was 51 . At that moment, feeling Mother’s 52 with feelings, I understood for the first time her being easy to 53 . She was still my mother, 54 she was something 55 : a person like me, capable of fear, 56 and failure. I could feel her pain as she must have felt mine on a thousand occasions when I sought 57 in her arms.
A week later Mother took a job selling dry goods at half the salary the radio station __58 .
“It’s a job I can do, though.” She said simply. But the evening practice on the green typewriter continued. I had a very 59 feeling now when I passed her door at night and heard her 60 away across the paper. I knew there was something more going on in there than a woman learning to type.

A．holding back

B．putting away

B．attentively

D．contributed

D．sympathetic

单项选择题

大脑是一个电化学场，在那里，有几十亿个神经元在不停地发出微小的电脉冲，正是那些携带和调节这些脉冲的化学物质，控制着人的身体、情绪和思想。对此，科学家们才刚刚开始有所了解。

化学家蒙特米尼在分析了大脑中一种关键的化学物质――生长激素释放的抑制因子的产生过程后发现，这种抑制因子太多时，就可能导致侏儒症和神经性食欲缺乏症；当这种抑制因子太少时，又可能导致压抑症和早老性痴呆。

蒙特米尼通过研究脑细胞里的基因后发现，人类喝咖啡之类的一些日常行为的刺激，有助于激活某个DNA片断，从而使生长激素释放的抑制因子得以产生。这个基因的开关是一种分子开关控制的，这种分子能阻碍DNA的工作，蒙特米尼分析出了这种“开关分子”，并且发现它是如何用化学方法来开启或关闭基因的。这方面的知识将有助于加速寻找治疗早老性痴呆症新方法的进程。

蒙特米尼的研究还可能导致其他新药，甚至治疗感冒的新药的产生。像他所发现的“开关”在感冒和其他种类的病毒中也存在，只要开发出一种新药来取代现在那些存在缺陷“开关”的药物，就能够防止感冒病毒的复制。

根据上文所述，下列陈述中，不正确的一项是（）。

A．蒙特米尼可能发现了压抑症产生的原因

B．蒙特米尼的研究可以用来治疗感冒

C．早老性痴呆与抑制因子太少有关

D．一些日常生活的刺激是因为DNA片断的刺激