专题03 八年级英语上册Unit 3 首字母填空提升训练(上海牛津版)

Passage One All sounds make waves. When you hear your friend’s voice, these sound waves go into your e I and you can identify(识别) your friend’s voice. U 2 , we cannot see sound waves but we can if we use some simple m 3 . Put a piece of tissue(纸巾) close to your l 4 and speak. Then you can see the tissue moving when you speak. If you speak loudly, the tissue moves more, and if you speak softly, the tissue moves less. This happens because the sound waves have vibration（振 动）． In s 5 , there are names for different sound waves. When the sound vibration is s 6 , we call this a low-pitch (音调) sound. But when the sound vibration is fast, we call this a high-pitch sound. Pitch d 7 how high or low a sound is. When the sound has less energy, we say it has a soft volume（音量）. But when the sound has more energy, we say it has a loud volume. Volume is a measure of how loud or soft a sound is. 答案：ears Usually materials lips science slow describes 【解析】 ea