问题
填空题
在中考期间，考场周边有“禁鸣喇叭、缓行，谢谢合作”的提示牌，噪声是由发声体的______振动产生的，“禁鸣喇叭”的提示是在______处减弱噪声．
答案
从物理学角度来说，噪声是发声体无规则振动产生的，“禁鸣喇叭”是在声源处减弱噪声的．
故答案为：无规则；声源．
搜题请搜索小程序“爱下问搜题”
在中考期间，考场周边有“禁鸣喇叭、缓行，谢谢合作”的提示牌，噪声是由发声体的______振动产生的，“禁鸣喇叭”的提示是在______处减弱噪声．
从物理学角度来说，噪声是发声体无规则振动产生的，“禁鸣喇叭”是在声源处减弱噪声的．
故答案为：无规则；声源．
| 用方框内所给单词的适当形式填空。 | |
old, only several years 2________ than me. In fact, some of them looked older and seemed more like grown-ups. And some of them even didn't listen to me 3________ in class. The classroom was on the second floor and it was directly above the street. One day, I was writing on the blackboard 4________ I heard a sudden change in the noise behind me. There was a man standing in the room with half an apple in his hand. He looked 5________. "Who threw this?" he shouted, looking around the class. "I beg your pardon?"I said. "6________ threw this apple out of the window." he said, "It landed on my car." "Who threw an apple out of the window?"I shouted to the class. There was no 7________. "I want the one who threw this." said the man,"I will be waiting outside for you."And then he left, slamming (摔) the door. There was silence and I went on 8________ the lesson. At the end of every lesson, as the bell rang, usually the class were all gone before it finished 9________, leaving me saying "That's all for today," to an empty room. This time, when the bell went for the end of the lesson, no one 10________."That's all for today," I said, "You go first, sir." said one of the boys. It made a nice change, being first out. |