入射光线与镜面夹角为40°时，反射角为，反射光线与入射光线夹角_爱下问搜题

搜题请搜索小程序“爱下问搜题”

问题填空题

入射光线与镜面夹角为40°时，反射角为，反射光线与入射光线夹角为60°时，入射角为。

答案

50⁰ 30⁰

考点：

分析：知道反射角是反射光线与法线的夹角．并掌握反射定律中两角之间的关系．

解答：解：入射光线与镜面的夹角为40°，所以入射角为90°-40°=50°．

反射光线与入射光线的夹角是60°，根据反射定律的内容，反射角等于入射角，所以入射角为30°．

故答案为：50°；30°．

点评：此题主要考查了发射角的概念及反射角与入射角之间的大小关系，是一道基础性题目．

单项选择题

解决人口老龄化问题，需要政府、社会和家庭共同努力。在传统中国，老人赡养在很大程度上属于子女义务，而不是政府责任。这种观念不仅会增加年青一代的负担，也会影响人力资源的最佳配置，同时有悖于以人为本的价值取向。将养老问题纳入社会统筹和政府责任范围，不仅会使老龄人口受益，也会减轻年青一代的负担。在这方面，一些发达国家已经探索出可以借鉴的成功经验。早在上世纪80年代，日本就在《国民年金法》、《老人福利法》和《老人保健法》的基础上，制定了《长寿社会对策大纲》，以致力于建立“具有活力的长寿社会”，并将其纳入社会整体部署。
通过这段文字，作者想表达的主要观点是( )。

A．要制定完备的法律法规体系来应对人口老龄化问题
B．中国传统重子女义务的养老模式存在弊端
C．我国养老问题的解决需要强调社会和政府责任
D．中国的养老模式与发达国家存在不小的差距

完形填空

完形填空（共20小题；每小题2分，满分40分）
One day a few years ago we had a guest of the uninvited variety. In fact, it was a bird,   1 a sparrow.
“What’s that?” I asked when I first heard the gentle thumping(重击声). “It sounds like Joe is outside playing basketball,” my wife, Anita, said. She   2  and listened more devotedly. “It’s coming from the 3 .” she said. “Maybe it’s one of the little kids.”
We rushed out the door. Jonathan, our youngest, was 4 to make trouble. “If he’s making holes in the wall again…” I said as I searched there. No children       5  . But there was that 6  again, coming from right up there.
And that’s when I 7  the sparrow. It was flying 8 just inches below the ceiling. It was 9 trying to get out, but couldn’t see that the way out wasn’t up, but down 10  the open door. So the bird continued 11  its wings and hitting its head against the 12 .
“Poor thing,” Anita said. “It must be 13  .”
“Well, maybe it’s because of us,” I said as I moved toward it. I tried to show the bird how to glide（滑翔） down to get outside, but that only seemed to 14   it more. “Why don’t we just 15 for a few minutes?” Anita suggested. “I’m sure he’ll    16 eventually.” So we went back into the house, where we continued to hear the ongoing 17  .Then suddenly, it was silent. We looked into the garage, and our uninvited guest was gone.
“See?” Anita said. “I told you he’d succeed.”
“Yeah,” I said. “But how many knocks on the head did it 18  him?”
I’ve thought about that little sparrow through the years. Just like that sparrow, we often meet situations we don’t know how to 19 . Born to go upward, we don’t even consider the possibility that something good might happen if we stop flapping（拍打）around and just glide 20 a little bit.

A．for example

B．rather than

B．unwillingly

A．put it aside

B．leave it alone

D．figure it out

B．achievement