题干

在“探究弹性势能的表达式”的活动中,为计算弹簧弹力所做的功,把拉伸弹簧的过程分为很多小段,拉力在每小段可以认为是恒力,用各小段做功的代数和代表弹力在整个过程所做的功,物理学中把这种研究方法叫做“微元法”。下列几个实例中应用到这一思想方法的是

A:在不需要考虑物体本身的大小和形状时,用点来代替物体,即质点

B:一个物体受到几个力共同作用产生的效果与某一个力产生的效果相同,这个力叫做那几个力的合力

C:在推导匀变数直线运动位移公式时,把整个运动过程划分成很多小段,每一小段近似看作匀速直线运动,然后把各小段的位移相加

D:在探究加速度与力和质量之间关系时,先保持质量不变探究加速度与力的关系,再保持力不变探究加速度与质量的关系

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答案(点此获取答案解析)

C

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阅读下列短文,从每题所给的A、B、C和D四个选项中,选出最佳选项,并在答题卡上将该项涂黑。

    Have you ever fancied sailing around the world or buying a holiday home in the Caribbean? Well, before you get too excited, it may help to find out if you have what it takes to become a billionaire.   

    We've all heard stories of school drop-outs who have made their fortune. Do they tend to be university graduates or self-made successful people? Are they married or single?

    Thanks to a recent analysis of people in Forbes(福布斯)Top 100 Billionaires List, we can now find out what they have in common. We know what percentage wear glasses and even how many are bald!

    If you are deciding whether or not to go to university, it may help you to know that 76% of the richest people in the world have a degree. According to this study, of those 76%, 47% have a bachelor's degree, 23% have a master's and 6% have a doctorate. Don't lose hope if you aren't very academic, though. It's worth noting that many of those on the list did not pass all their exams with flying colors. Microsoft founder Bill Gates dropped out of Harvard University after two years of study. And Chinese business magnate Jack Ma, failed his university entrance exams three times before going on to complete his degree and make his millions.

    Another interesting trend is that the world's richest people are much more likely to be married - only 12% of billionaires are unmarried. Finally, the percentage of billionaires who are bald is quite high – so don't worry if you're losing your hair.