题目

一列波由波源向同围扩展，则以下说法中正确的有       A．介质中各质点由波源向周围运动       B．介质振动的能量由波源向周围传播       C．介质中各质点振动的形式由波源向周围传播       D．介质中各质点只是在各自的平衡附近振动而没有发生迁移 答案：BCD 解析:波在传播过程中，质点的振动形式和能量向远处传播，而质点不随波迁移。答案为：B、C、D   根据下面的图示，用适当的方位介词填空1.The clown (小丑) is standing the ball now. He is looking at us.2.The clown can jump high.Look!The ball is him.3.Now,he is the table. What is he thinking about now?4.He is standing the drum (妓) now. Is he going to play it?5.He is standing the drum.Is he going to jump down?6.He is now the ball and he doesn’t look happy.7.There are two flowers in the picture.The clown is standing the flowers.8.He is sitting the big box.9.There is a chair the clown.Do you want to sit on it?