题目

There is an old English saying. Have you heard it before? It says that we must go to bed early and get up early in the morning. Then we should be healthy. We should also be wealthy (富有的) and clever. This is true. The body must have enough sleep to be healthy. Children of a young age should have ten hours’ sleep every night. Children who don’t have enough sleep can’t do their work very well. They will not be wise and they may not become wealthy!     The body also needs exercise. Walking, running, jumping, swimming and playing games are all exercise. Exercise keeps the body 如图所示的凸透镜，若把它用在书写投影仪上，则物体应放的位置为（ ）A．A点B．B点C．C点D．E点