阅读理解。 The class was coming to an end. The teacher told the pupils not to draw anything on the wall in order to keep it clean. After class, David forgot the teacher's words. He took a piece of chalk and drew a sun on the wall. Just then, he noticed that the teacher was coming back again. So he quickly covered his drawing with his back. The teacher didn't find out what he was doing. When she passed, she smiled at David. David was very happy. But when he turned around to see his drawing, he found nothing on the wall. Where was David's drawing? 1. The teacher told the pupils _______. [     ] A. to keep quiet after class B. not to draw on the wall C. not to stand against the wall 2. After the class was over, David _______. [     ] A. went back home B. picked up a piece of chalk C. drew a sun on the wall 3. When David noticed the teacher coming, _______. [     ] A. he covered the drawing with his back B. he cleaned the wall with his hand C. he turned around and ran away 4. What did David find on the wall after the teacher left? [     ] A. He found a sun on the wall. B. He found a picture on the wall. C. He found nothing on the wall. 5. Where was David's drawing at last? [     ] A. It was on the wall. B. It was on David's back. C. It was taken away by his teacher.