题目

一列简谐波在传播方向上相距x=3m的两质点P、Q的振动图像如图所示．这列波的波长可能是（    ） A．4m B．8m C．12m D．16m 答案：AC 解析:由于P、Q两点离波源的远、近不明确，因此要分两种情况讨论。 1．若P比Q离波源近，则P先振动。比较t=0时两质点的位移可知，Q比P落后的时间为 ，（n=0，1，2，…） 则， 得， 当n=0时，λ=4m； 当n=1时，λ=m/s； … 随着n取值的增大，波长λ变短．这种情况下最大波长为λ=4m。 2．若Q比P离波源近，则Q第II卷(非选择题 共35分)注意：将答案写在答题卡上，写在本试卷上无效。第三部分：写作(共两节，满分35分)第一节：短文改错 (共10小题；每小题1分，满分10分)假如英语课上老师要求同学们交换修改作文，请你修改你同桌的以下作文。文中共有10处语言错误，每句中最多两处。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(∧)，并在其下面写出应加的词。删除：把多余的词用斜线(＼)划掉。修改：在错的词下划一横线，并在其下面写出修改后的词。注意：1．每处错误及其修改均仅限一词。 2．只允许修改10处，多者(从十一处起)不计分。China is an ancient civilization with cultures dating back more than 4，000 year．Basic elements for the modern world such as paper，gunpowder，paper money，or compasses originated in China．Today，China is again at the forefront of world，with Chinese goods reach all parts of the world．The Chinese culture have also fascinated many people．In the Shaolin Monasteries，the Great Wall of China or the Forbidden City of Beijing，China has its unique arts and architectures that what draw thousands of visitors every year．The Chinese food is equal popular around the world and it is loved by much non-Chinese．But in China，the food can found in great varieties and is different in region to region．So join us and experience all these．