下列哪些现象是明显的衍射现象()A.“隔墙有耳”B.池中假山前有水波,假山后无水波C.池中芦苇后面有水波D.在大山前喊话,多次听到自己的声音 答案:AC【试题分析】【解析】 “隔墙有耳”是声波通过缝隙发生衍射;假山后无水波是由于波被假山阻隔;芦苇后有水波是水波发生衍射;大山前听到回声是由于声波的多次反射.正确选项为A、C.
Such expressions are often used in ________ countries, so try to learn them by heart.
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A.speaking-English
B.English-speaking
C.English-spoken
D.spoken-English