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问题 选择题

下列现象中属于光的反射现象的是（　　）

A．凸透镜成像

B．平静的水面上看到树的倒影

C．小孔成像

D．插在水中的筷子看起来弯折了

答案

A、凸透镜成像，属于光的折射现象，不符合题意．

B、平静的水中映出树的倒立的像，属于平面镜成像，是光的反射原理，符合题意；

C、小孔成像是由于光的直线传播，不符合题意．

D、斜插入水中的筷子看起来向上弯折，是由于光线从水中斜射入空气中时发生了折射．不符合题意．

故选B．

阅读理解


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填空题

先来先服务、短作业优先、最高响应比优先、优先数法调度算法中最短的作业平均周转时间是 【7】 。
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