阅读下面短文，掌握大意，然后从1-20各题所给的四个选项（A、B、C和D）中，选出最佳答案。

         A young student was one day taking a walk with a professor, who was commonly  1the students’ friend. As they went  2 , they saw lying in the path a pair of old   3  , which they supposed to belong to a poor man who was employed in a 4 close by. The student turned to the professor, saying, “Let’s play the man a5 ,We will hide his shoes, and 6ourselves behind those bushes, and wait to see his 7when he cannot find them.”

     “My young friend,” answered the professor, “we should never8ourselves at the 9of the poor. But you are 10, and may give yourself a much greater11by means of the poor man. Put a coin into each shoe, and then we will hide ourselves and 12how the discovery affects him.” The student did so, and they both placed themselves behind the bushes. The poor man soon finished his work, and came13the field to the path 14 he had left his coat and shoes. While15his coat he slipped his foot into one of his shoes; but feeling 16, he stopped down to feel  17it was, and found the coin. Astonishment and wonder were seen upon his face. He now put the money into his pocket, but his  18was doubled on finding the other coin. He fell upon his knees, looked up to heaven and uttered aloud a fervent（热烈的）thanksgiving, in which he19 his wife, sick and helpless, and his children without bread. The student stood there deeply 20, and his eyes filled with tears.