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问题 选择题

如图(a)所示,一根细线上端固定在S点,下端连一小铁球A,让小铁球在水平面内做匀速圆周运动,此装置构成一圆锥摆(不计空气阻力).下列说法中正确的是：（  ）

A．小球做匀速圆周运动时的角速度一定大于(l为摆长)

B．小球做匀速圆周运动时，受到重力，绳子拉力和向心力作用.

C．另有一个圆锥摆，摆长更大一点，两者悬点相同.如图(b)所示，如果改变两小球的角速度，使两者恰好在同一水平面内做匀速圆周运动，则B球的角速度等于A球的角速度

D．如果两个小球的质量相等,则在图(b)中两条细线受到的拉力相等

答案

AC

题目分析: 由圆周运动规律可得：，解得，故A正确；匀速圆周运动的向心力是由合力提供的，小球做匀速圆周运动时，受到重力、绳子的拉力，其合力充当向心力，故B错误；由，可知，由于高度相同，B球的角速度等于于A球的角速度，故C正确；拉力，由于θB＞θA，如果两个小球的质量相等，则在图乙中两条细线受到的拉力应该是A细线受到的拉力大，故D错误。

单项选择题

根据现行部颁规定，水利工程项目一般划分为三级项目，其中二级项目相当于（）。

A.单项工程

B.单位工程

C.分部工程

D.分项工程
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完形填空

SECTION B (10 points)

Direction: Read the following passage and answer the questions according to the information you get in the passage and the required words limit.

Several years ago, Masaru Ibuka, the chairman of Sony, was at a company planning a meeting. Suddenly he had a brilliant idea. He stopped the meeting and asked everyone present what would happen if Sony removed the recording function and speaker and sold headphones(耳机) with a tape player instead. Almost everyone thought he was crazy. Still, Ibuka kept thinking about his idea and worked at refining it. The result, of course, turned out to be the wildly successful Sony Walkman.

Good ideas often start with a really silly question. Bill Bowerman was making breakfast one day. As he stood there making waffles(蛋奶烙饼)for his son, he wondered what would happen if he poured rubber into his waffle iron(蛋奶烙饼烤模).So, he tried and the result looked something like the bottom of most sports shoes we see today. Still, when he took this idea to several existing shoe companies he was literally(确实地)laughed at. In fact, every single company turned him down. Though rather disappointed, Bowerman was determined and went on to form his own company, making NIKE athletic shoes.

Sometimes good ideas grow out of frustration(挫败). When Fred Smith was a student at Yale University, he had some paperwork that he needed to have delivered across the country the next day. Smith was amazed to find out that overnight delivery(隔夜送货) was impossible. He sat for a long while wondering why. Why couldn’t there be reliable overnight mail delivery service? He decided to design one. Smith did just that and turned his design into a class project. His business professor thought it was not a good class project and gave him only a C. However, Smith refined the idea in that class project and eventually turned it into one of the first and most successful overnight mail services in the world——FedEx.

81. What did Masaru Ibuka’s idea turn out to be? （no more than 2 words）

______________________________________________________________________________

82. What did Fred Smith’s teacher think of his class project? （no more than 8 words）

______________________________________________________________________________

83. Nike athletic shoes came from Bill Bowerman’s idea of____________. （no more than 6 words）

______________________________________________________________________________

84. What is the main idea of the passage? （no more than 12 words）

______________________________________________________________________________
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