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问题 选择题

我国发射的第一颗探月卫星“嫦娥一号”，进入距月面高度h的圆形轨道正常运行。已知月球半径为R，月球表面的重力加速度为g，万有引力常量为G，则嫦娥一号绕月球运行的周期为          

B．嫦娥一号绕行的速度为

C．嫦娥一号绕月球运行的角速度为   

D．嫦娥一号轨道处的重力加速度

答案

CD

题目分析：设月球质量为M，卫星质量为m，在月球表面上，万有引力约等于其重力有： ,卫星在高为h的轨道上运行时，万有引力提供向心力有：

 ,

由上二式算出g1、v、 、T可知AB错，CD正确，所以本题选择CD。

问答题

As a scourge of the modern society, obesity has become the world’s biggest public-health issue today — the main cause of heart disease, which kills more people these days than AIDS, malaria, war. Since the World Health Organization labeled obesity an "epidemic" in 2000, reports on its fearful consequences have come thick and fast. Will public-health warnings, combined with media pressure, persuade people to get thinner, just as they finally put them off tobacco Possibly. In the rich world, sales of healthier foods are booming and new figures suggest that over the past year Americans got very slightly thinner for the first time in recorded history. But even if Americans are losing a few ounces, it will be many years before the country solves the health problems caused by half a century’s dining to excess. And, everywhere else in the world, people are still piling on the pounds. That’s why there is now a consensus among doctors that governments should do something to stop them.
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单项选择题 A1型题

下述有关糖、脂肪、蛋白质互变的叙述中，哪项错误（）

A.蛋白质可转变为糖

B.脂肪可转变为蛋白质

C.糖可转变为脂肪

D.葡萄糖可转变为非必需氨基酸的碳架部分

E.脂肪中甘油可转变为糖
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