问题
单项选择题
声波能绕过某一建筑物传播而光波却不能绕过该建筑物，这是因为( )．
A．声波是纵波，光波是横波
B．声波振幅大，光波振幅小
C．声波波长较长，光波波长较短
D．声波波速较小，光波波速很大
答案
参考答案：C
解析： 建筑物尺度比较大，声波的波长与它相比，相差不大，能发生明显的衍射现象，而光波波长要小的多，不能发生明显的衍射，故C项正确．
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声波能绕过某一建筑物传播而光波却不能绕过该建筑物，这是因为( )．
A．声波是纵波，光波是横波
B．声波振幅大，光波振幅小
C．声波波长较长，光波波长较短
D．声波波速较小，光波波速很大
参考答案：C
解析： 建筑物尺度比较大，声波的波长与它相比，相差不大，能发生明显的衍射现象，而光波波长要小的多，不能发生明显的衍射，故C项正确．
What can you do in two minutes? Cyrus Siu, 12, made a great speech in English and the hearts of everyone. Siu studies at Singapore International School in Hong Kong. He the Junior high category (初中组) of the 11th “21st Century Cup” National High School and Primary School English Speaking Competition in Xiamen, Fujian March 22. His speaking skills and good English won him the top . Siu said his first secret to success was many English books. He has read all the seven Harry Potter books, each four to five . Now he is reading Steve Jobs: A Biography(《乔布斯传》) “These books may be for my age, but reading helps to learn new words,” he said. Siu likes movies. Super hero movies, Iron Man(《钢铁侠》) and The Avengers(《复仇者联盟》), are his favorite. “Every boy has the dream of becoming a super one day. Sometimes I imagine to be one of the heroes and shout out the English lines(台词). It’s good to combine(结合) your with learning English. It’s also important to an English-speaking environment for yourself. Siu talks to his classmates and teachers in English all day long at school. his parents talk to him in Cantonese(粤语) at home, he still tries to answer in English. “There is no shortcut(捷径) to studying English. Just practice, practice and practice!” Siu said.
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