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问题 选择题

如图所示，在调节平衡后的杠杆两侧，分别挂上相同规格的钩码，杠杆处于平衡状态．如果两侧各去掉一个钩码，则

A．左端下降

B．右端下降

C．仍然平衡

D．无法判断

答案

答案：B

题目分析：设一个钩码的重为G，每一格的长度为L，则原来杠杆：2G×6L=3G×4L，处于平衡状态，现在杠杆两侧各去掉一个钩码后，左边力与力臂的乘积=G×6L，右边力与力臂的乘积=2G×4L，右边的力和力臂的乘积大，杠杆不再平衡，并且右端下降．

本题答案选B．

填空题

用列举法表示方程x2-5x+6=0的解集为______．
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听力题

短文填空 先通读下面的短文，然后根据短文内容和所给首字母，在空格内填入一个适当的单词，使短文意思完整。所填单词必须在答卷标有题号的横线上完整写出。（本大题共10空，每空0.5 分，共5分）

According to the school rules, students shall wear school uniforms. H       小题1:, for most students, school uniforms are not w       小题2:they like. “Why not wear the school uniform just one day a week? Always wearing the same clothes makes me feel b      小题3:of them.” A senior sutdent from a high school said. Most studetns don’t like the school uniforms’ s       小题4:colors, boring designs and bad quality. And a teacher at a high school in Guangzhou said. “ A      小题5:a teacher and mother, I hope the quality of school uniforms will be i       小题6:soon.” What has caused all these problems? Chen Hong, a uniform designer in Shenzhen, pointed out. “There are no professionals (专业人员) who work for students. “Besides, high quality m        小题7: a high price.” said Chen. “But in some schools the price for each student’s uniform is only 50 to 60 yuan. How can we p     小题8:high quality clothes with so little money?”

Even with these problems, e       小题9:has been put into changing the situation. It won’t be long b       小题10:the perfect school uniforms come onto the market, which will remind the students of the values and history of their school and make them take pride in their school.
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