题目

一重球从高h处下落，如图所示，到A点时接触弹簧，压缩弹簧至最低点位置B.那么重球从A至B的运动过程中：A.速度一直减小B.速度先增加后减小C.在AB之间有个确切位置速度有最大值D.加速度方向先竖直向下再竖直向上 答案：【答案】BCD【解析】小球刚开始与弹簧接触过程中，在时，小球受到的合力竖直向下，所以仍做加速运动，随着弹簧压缩量的增大，向下的加速度在减小，当时，加速度为零，速度达到最大，当时，小球受到的合力方向向上，所以小球做减速运动，并且加速度在增大，当压缩至最低点时，速度为零．故B In public places, people often use body language to express their meanings. Waving and bowing are examples of body language. Different kinds of body languages show different cultures in different countries. In China waving means greeting, but in Japan bowing is used. Sometimes this kind of body language is polite in one country, but it is not polite in another. We should pay attention to using it. In China, nodding your head shows you agree with someone, but in India, shaking your head from side to side shows agreement. In China, people hold hands as a sign of friendship, but people seldom hold hands in North America. It is worth(值得) noting that different meanings of body language can also cause problems in understanding. Some people do not understand how to use thumb(拇指) correctly. Most people often show one thumb to praise someone or something. You can't raise your thumb when someone is in danger. In a basketball match, if the judge shows two thumbs, it means two players break the rules.1.Where do people often use body language?A.In a basketball match. B.At the square.C.At the station. D.In public places.2.Different kinds of body language show ________ in different countries.A.different cultures B.the same culture C.different habits D.the same social custom3.How many kinds of body language are mentioned(提到) in the passage?A.5. B.6. C.7. D.8.4.Which of the following is TRUE according to the passage?A.In a basketball match, you can show two thumbs to praise the players.B.In China, nodding your head shows you disagree with someone.C.Body language can show different cultures.D.Different meanings of body language can solve the problems.5.The main idea of this article is about ___________.A.nodding your head B.body language and cultureC.body language and countries D.raising your thumbs