题目

     This is a street crossing. There are red and green lights at each corner. Drivers must watch the lights carefully.      When there is a green light, the car may go on. When there is a red light, the cars must stop. They must wait until the red light changes to green. Then they can go on. Sometime the cars want to make a right turn or a left turn. They can make a right turn when the light is green or red . But they must wait until the green light is shining if they want to turn left.      Some people are color-blind(色盲).they cannot see the difference between red and16．运用知识解决问题（1）如图所示，蛋糕小朋友在艺术节上用古筝弹奏优美的乐曲，乐曲的声音是通过空气传入人耳的；蛋糕小朋友用力拨动古筝弦可以增大古筝弦的振幅来提高声音的响度；下面的观众能辨别出她弹的是古筝乐曲，这是通过声音的音色来判断的．（2）雷雨天，麻花同学看到闪电后过了4秒才听到了隆隆的雷声，则发生雷电的位置距离她的距离大约是1360m；她先看到闪电后听到雷声，这是光的传播速度远大于声音的传播速度造成的．（忽略光传播所用的时间，当时的气温是15℃）（3）教室里，茶蛋同学坐在自己的位置上，看到黑板上有的地方“反光”而看不清上面的字，这是因为光在黑板上发生了镜面反射．