如图所示，山区盘山公路的路面边上一般都等间距地镶嵌一些小玻璃

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问题计算题

如图所示，山区盘山公路的路面边上一般都等间距地镶嵌一些小玻璃球，当夜间行驶的汽车的车灯照上后显得非常醒目，以提醒司机注意.若小玻璃球的半径为R，折射率是，今有一束平行光沿直径AB方向照在小玻璃球上，试求离AB多远的入射光经折射-反射-折射，再射出后沿原方向返回即实现“逆向反射”？

答案

解：光路如图所示，由几何关系知

θ₁=2θ₂

n==2cosθ₂=

解得cosθ₂=，θ₂=30°

θ₁=60°，sinθ₁=

d=Rsinθ₁=R

填空题

背诵。

1. Young children might Superman or Batman while adults might picture a doctor or police officer.

2. Beth a respiratory problem which made it difficult for her to breathe.

3. She grew up in and out of hospitals where she devices to help control her illness.

4. But she was determined, and when her eleventh birthday , Beth was there to her candles.

5. She proved the doctors wrong but, even though she lived past the , she still wasn't .

6. Beth went through several more years of nurses and doctors poking her like but she never

complained.

7. With all she had to deal with, you would think she would be too busy to listen to her

friends' -nevertheless she always found time

单项选择题

某企业购入W上市公司股票180万股，并划分为交易性金融资产，共支付款项2830万元，其中包括已宣告但尚未发放的现金股利126万元。另外，支付相关交易费用4万元。该项交易性金融资产的入账价值为（）万元。

A.2700

B.2704

C.2830

D.2834