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问题 计算题

（10分）如图所示，在海滨游乐场里有一种滑沙运动。某人坐在滑板上从斜坡的高处A点由静止开始滑下，滑到斜坡底端B点后，沿水平的滑道再滑行一段距离到C点停下来。若人和滑板的总质量m="70.0" kg，滑板与斜坡滑道和水平滑道间的动摩擦因数均为μ=0.50，斜坡的倾角θ=37°（sin37°=0.6，cos37° = 0.8），斜坡与水平滑道间是平滑连接的，整个运动过程中空气阻力忽略不计，重力加速度g取10 m/s2。求：

（1）人从斜坡上滑下的加速度大小为多少；

（2）若AB的长度为25m,求BC的长度为多少。

答案

（1）（2）10m

题目分析：（1）人在斜面上受力如图所示，建立图示坐标系，设人在斜坡上滑下的加速度为a1，由牛顿第二定律有

又

联立解得　

（2）人滑到B点时

在水平轨道上运动时

由

 

单项选择题

(二) For any Englishman, there can never be any discussion as to who is the world’s greatest dramatist. Only one name can possibly suggest itself to him : that of William Shakespeare. Every Englishman has some knowledge, however slight, of the work of the greatest writer. All of us use words, phrases and quotations from Shakespeare’ s writings that have become part of the common property of theEnglish - speaking people. Most of the time we are probably unaware of the source of the words we used, rather like the old lady who was taken to see a performance of Hamlet and complained that it was full of wellknown proverbs and quotations. Shakespeare, more perhaps than any other writer, makes full use of the great resources of the English language. Most of us use about five thousand words in our normal use of English; Shakespeare in his works used about twentyfive thousand. There is probably no better way for a foreigner to appreciate the richness and variety of the English language than by studying the various ways in which Shakespeare used it. Such study is well worth the effort (it is not, of course, recommended to beginners) even though some aspects of English usage, and the meaning of many words, have changed since Shakespeare’ s day.

Why is it worthwhile to study the various ways in which Shakespeare used English______

A．English words have changed a lot since Shakespeare’s times.

B．By doing so one can be fully aware of the richness of the English language.

C．English words are now being used in the same way as in Shakespeare’s times.

D． Beginners may have difficulty learning some aspects of English usage.
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问答题

一家咨询公司受某钢铁厂委托，为其所在地区的钢铁消费市场进行分析和预测。为了收集数据，咨询公司分别走访了钢铁工业协会、钢铁研究院和省、市统计局等相关部门，并收集到了该地区2009～2011年的钢铁销售额数据，见表5。


问题：


根据表5给出的数据，你认为是否适合采用季节指数水平法进行预测，为什么
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