生活、生产中常用到光学知识：在开凿大山隧道中，用激光引导掘进机掘进方向，如图所示，是利用了光沿____；有时人们把电视机遥控器的红外线发射窗，对着电视机对面墙壁发射，也能控制电视机，这是利用了光的____现象；有经验的渔民都知道，只有瞄准鱼的下方才能把鱼叉到，这是利用了光的____现象；照相机是利用凸透镜成倒立、缩小、____像的性质制成的．

根据短文理解，从A、B、C、D四个选项中选择最佳答案填空。

    Somebody says, “Time is money.” But I think time is 1 important than money. Why do I think so? Because when money is over, we can get it back. But when time is 2, it'll never be 3. That's 4 we shouldn't waste time.

    It goes with saying that the 5 is usually limited（有限的）. Even a second（秒） is very important. We should make full use of our time to do 6 useful.

    But a lot of people do not know the importance of time. It is a pity. They spend their limited time smoking, drinking, sleeping and 7. They do not know that wasting time means wasting part of their own 8.

    In a word, we should save time. We shouldn't 9 today's work for tomorrow. Please remember that we have 10 time to waste.

1942年2月14日，蒋介石在致罗斯福感谢美国对华贷款5亿美元的电文中说：“此次借款，除为军事上之需要外，大部分将用以加强我国之经济机构，收回法币，紧缩通货，平定物价，保持战时生活水准及增加生产。”这表明当时的蒋介石国民政府（　　）

下列关于声现象的说法正确的是（　　）