问题 不定项选择

如图所示,从地面上A点发射一枚远程弹道导弹,在引力作用下,沿ACB椭圆轨道飞行击中地面目标B,C为轨道的远地点,距地面高度为h。已知地球半径为R,地球质量为M,引力常量为G,设距地面高度为h的圆轨道上卫星运动周期为To。下列结论正确的是

[ ]

A.导弹在C点的速度大于

B.导弹在C点的加速度等于

C.地球球心为导弹椭圆轨道的一个焦点

D.导弹从A点运动到B点的时间一定小于T0

答案

BCD

阅读理解

[1]One out of many important things for the whole family to do is to have dinner together. Researchers began reporting the benefits of family dinner about a decade ago, focusing mainly on how it affects children. Studies show that those families who eat dinner at least 3 or 4 times a week together, benefit in many ways.

[2]Eating together helps families achieve open communication and build stronger and healthier relationships. Children have better grades at school and are better adjusted as teens and adults, and the entire family enjoys healthier nutrition. For many families, eating dinner together proves to be good and effective way to reduce the risk of youth rates of addiction, and helps to raise healthier children. It is also a great time to share the events of the day, discuss news and ideas and just be together and enjoy each other's company.

[3]During dinner time parents have better opportunity to show that the prior to their children. Sitting at the same table and sharing meals is where and when parents can find out more about their children's school performance, daily activities and attitudes toward life. When parents have all this information they can better direct their kids toward positive things in life. They also have better chance to reduce the possibility that children will get involved with alcohol, tobacco, and illegal drugs.

[4]However, family researchers say that the benefits of family dinner by no means can be considered as automatic. Parents can sit down to dinner with their kids every day and achieve nothing. _________ if there is too much arguing going on, if there is no meaningful conversation or, what is even worse, if there is just plain silence during gathering.

小题1:What is the main idea of the text? (no more than 8 words)

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小题2:What is the author’s attitude to family dinner?(no more than 2 words)

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小题3:Fill in the blank in Paragraph 4 with proper words. (no more than 8 words)

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小题4:What information can parents probably get about their children at family dinner? (no more than 12 words)

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小题5:What does the word underlined in Para. 3 refer to.(No more than 2 words)?

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选择题