（6分）如图a是“研究影响滑动摩擦力大小的因素”实验．（1_爱下问搜题

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问题实验题

（6分）如图a是“研究影响滑动摩擦力大小的因素”实验．

（1）实验过程中，弹簧测力计（选填“必须”或“不必”）沿水平方向拉着物块做匀速直线运动，此时，滑动摩擦力的大小（选填“大于”、“等于”或“小于”）弹簧测力计示数．

（2）在三次实验中，滑动摩擦力最大的是（选填“甲”、“乙”或“丙”）．

（3）比较甲、乙实验，是为了研究滑动摩擦力大小与有关；比较乙、丙实验，是为了研究滑动摩擦力大小与有关（以上两空选填“压力”或“接触面粗糙程度”）．

（4）小丽同学对实验装置进行改动，如图b所示，重复实验，发现效果更好．实验中，小丽同学（选填“一定”或“不一定”）要匀速拉动长木板．

答案

（1）必须；等于；（2）丙；（3）压力；接触面粗糙程度；（4）不一定．

题目分析：（1）实验过程中，弹簧测力计必须沿水平方向拉着物块做匀速直线运动，此时，拉力与摩擦力是一对平衡力，滑动摩擦力的大小等于弹簧测力计示数。

（2）由图a可知，甲中的滑动摩擦力是1.5N，乙中的滑动摩擦力是2N，丙中的滑动摩擦力是2.5N。滑动摩擦力最大的是丙。

（3）甲、乙实验，接触面的粗糙程度相同，压力不同，是为了研究滑动摩擦力大小与压力大小有关。

乙、丙实验，压力相同，接触面的粗糙程度不同，是为了研究滑动摩擦力大小与接触面粗糙程度有关。

（4）由图b知，木块固定，抽动木板，不一定要匀速拉动长木板，但木块总会处于静止状态，受到的摩擦力与拉力始终是平衡力，大小相等。

完形填空

阅读下面短文，从短文后各题所给的四个选项A、B、C和D中，选出可以填入空白处的最佳选项，并在答题卡上将该项涂黑。
When I was fifteen, I announced to my English class that I was going to write my own books. Half the students sneered（冷笑）, the   nearly fell out of their chairs laughing. “Don’t be silly, only    can become writers, ” the English teacher said, “And you are getting a D this term. ” I was so    that I burst into tears.
That night I wrote a short   poem about broken dreams and mailed it to the newspaper. To my   , they published it and sent me two dollars. I was a published and   writer. I showed my teacher and fellow students. They   . “Just plain dumb luck. ” the teacher said. I tasted   and I’d sold the first thing I’d ever written. That was more than any of them had done and if it was just dumb luck, that was   with me.
During the next two years I sold dozens of   , letters, jokes and recipes. By the time I    from high school, with a C minus average, I had scrapbooks（剪贴簿） filled with my published works. I    mentioned my writing to my teachers, friends or my family again. They were dream killers and   people must choose between their friends and their dreams, they must always choose their     .
I had four children at the time, and the oldest was only four. I wrote what I felt. It   nine months, just like a pregnant woman. I mailed it without a self addressed stamped   and without making a copy of the manuscript(原稿).
A month later I received a（n）   , and a request to start working on another book. The worst year I earned two dollars. In my best year I earned 36, 000 dollars.      years I earned between five thousand and ten thousand. No, it isn’t enough to live    , but it’s still more than I’d make working part time. People ask what college I    , what degrees I had and what qualifications I have to be a writer. The answer is： “None. ” I just write. I’m not a genius.

C．disappointing

B．astonishment

A．dropped out

判断题

行为人具有相应的民事行为能力是民事法律行为成立的实质要件之一。 ( )