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问题 选择题

两个同高度斜面，倾角分别为α、β，小球1、2分别由斜面顶端以相等水平速度抛出，如图所示，假设两球能落在斜面上，则飞行的高度之比为（   ）

A．1:1

B．tanα:tanβ

C．tanβ:tanα

D．tan2α:tan2β

答案

答案：D

设两球平抛运动的初速度为v0，则

对于球1：tanα==，得到运动时间t1=2，下落高度h1=g

同理，得到球2运动时间t2=2，下落高度h2=g 则得到h1：h2=tan2α：tan2β

阅读理解

C

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单项选择题

一般尿毒症，下列哪项是正确的（）。

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C、小细胞低色素性贫血

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E、血钾均增高
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