将长为l的玻璃圆柱体沿轴剖开后得到一块半圆柱体，其截面的正视图如图所示，MNPQ为其底面（PQ图中未画出），MN为直径．已知半圆的圆心为O、半径为R，玻璃的折射率n= $\sqrt{2}$ ．一束与MNPQ所在平面成45°且垂直于轴的平行光束射到半圆柱面上，经折射后，有部分光能从MNPQ面射出，忽略经多次反射到达MNPQ面的光线，求MNPQ透光部分的面积．

阅读理解

    Mr. White's family decided to repair their house. Mr. White bought the house two and a half years ago. Since his kids were growing up, he and his wife wanted to make some changes to the house.

    They decided to knock down their living room wall to open up the space. When the wooden walls were moved, they were shocked to find a lizard (蜥蜴) stuck in the small space between the walls. The lizard's foot was stuck by a nail (钉子) which was knocked into the wall from the other side several months ago. However, they wondered how the lizard had survived so long without moving from that place.

    The family decided to wait for a while and see how the lizard survived several months without moving. While they were doing other things, they kept an eye on the lizard. The son, Ray, suddenly shouted, “Dad, look here!”

    Another lizard appeared, carrying food to the stuck lizard's mouth. That was a real surprise! Everyone was touched that the lizard fed the other one for all this time.

    Both lizards had never-ending hope for each other and carried their hearts with love and care. Why can't we humans always carry that kind of love in our hearts? Life is full of all kinds of difficulties. What we can do is to give our hand to the one in need and share our love. Sharing is caring.

下列命题正确的是（　　）

读图，完成下列各题：

有三个点A，B，C，过其中每两个点画直线，可以画出直线（　　）