题目

关于声现象，下列说法正确的是（ ）A. 二胡演奏出的乐音，是由弦的振动产生的B. 声音和光在空气中传播时，声音传播的较快C. 声音在空气中传播比在水中传播得快D. 跳广场舞时喇叭播放的歌曲都是乐音 答案：【答案】A【解析】A、二胡演奏出的乐音，是由弦的振动产生的，故A正确；B、声音在空气中的速度约为340m/s，光在空气中的传播速度为3.0×108m/s，由此可知光的传播速度远大于声音的传播速度，故B错误；C、一般地，声音在固体中传播的最快，在液体中次之，在空气中传播的最慢，故C错误；D、跳广场舞短文改错（共10小题，每小题1分，满分10分）文中共有10处语言错误，每句中最多有两处。错误涉及一个单词的增加、删除或修改。增加：在缺词处加一个漏字符号（?），并在其下面写出该加的词。删除：把多余的词用斜线（\）划掉。修改：在错的词下划一横线，并在该词下面写出修改后的词。注意：1. 每处错误及其修改仅限一词； 2. 只允许修改10处，多者（从第11处起）不计分。Today I attended a meeting holding by our school. At the meeting more than thirty studentspraised. For our happiness, Bruce, monitor of our class, who was among them. We all felt proud of him. Then the headmaster gave them a talk. He wanted us to learn these model students and hoped that more and more students will be praised at the next school meeting.I was great encouraged and make up my mind to work harder. Next week there will be an English exam. I’ll try to get good mark.