问题
选择题
如图所示，某同学朝着列车行进方向坐在车厢中，水平桌面上放有一静止的小球．突然，他发现小球相对桌面向后滚动，则可判断（ ）
A．列车在刹车
B．列车在做加速直线运动
C．列车在做减速直线运动
D．列车在做匀速直线运动
答案
当列车加速时，小球由于惯性要保持原来的运动状态，相对于小车向后运动，即我们观察到的现象；
故列出突然加速；
故选B．
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如图所示，某同学朝着列车行进方向坐在车厢中，水平桌面上放有一静止的小球．突然，他发现小球相对桌面向后滚动，则可判断（ ）
A．列车在刹车
B．列车在做加速直线运动
C．列车在做减速直线运动
D．列车在做匀速直线运动
当列车加速时，小球由于惯性要保持原来的运动状态，相对于小车向后运动，即我们观察到的现象；
故列出突然加速；
故选B．
“USA? Britain? Which country is better to study in?” We often hear such discussions. As China open its door, it is a dream for many Chinese students to study abroad. They want to learn about the outside world. It’s true that studying abroad can help students develop themselves. Their foreign language skills will be improved and it may be easier to find jobs. But there are problems that should be considered. Language is the first. Students must spend a lot of time learning another language. Students must also learn to live without parents’ care and deal with all kinds of things they haven’t to do before, like looking after themselves. There are reports about Chineses students abroad running into an ocean of difficulties and giving up finally. When they have to take care of themselves, it is hard for students to study well. Finally, studying abroad brings a heavy burden to the family. For most Chinese parents, the cost of studying abroad is very high. But is it worth it? We know that there are many famous people who have achieved success through their hard work in China. Liu Xiang is a good example. Once an American teacher invited him there, but he refused. He kept training hard with his Chinese teacher. He surprised the world when he won a gold medal at the Athens Olympic Games. So when you winder which country is better to study in, think it again.
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