阅读下面短文，掌握其大意，然后从16-35各题所给的四个选项中，选出最佳选项，将短文内容补充完整。

One day, a poor boy, named Howard Kelly, was trying to pay his way through school by selling goods door to door. He was hungry,  (1)  he decided to beg something to eat. When a young woman opened the door, instead of a   (2)  he asked for a drink of water. Thinking he looked   (3)   she brought him a large glass of milk．He drank it and then asked, “How much do I   (4)   you?”

    “No, you don’t owe me anything,” she replied. “Mother has taught me  (5)  accept pay for a kindness. ”Leaving that house, he not only felt stronger  (6)  , but it also increased his faith in God and the human race. He was about to  (7)  before this point.

      (8)   later the young woman became seriously ill. The local doctors couldn’t cure her illness. They sent her to the big city, where specialists can be   (9)  to study her disease. Dr. Howard Kelly, now  (10)  , came for the consultation(会诊). When he heard the name of the town where she came from, a strange light filled his eyes.   (11)  , he went into her room.

      (12)   in his doctor’s gown (罩衣)， he went in to seeher. He   (13)   her at once. He went back to the  (14)  and determined to do his best to save her life．From that day on，he gave special attention to her case.

Finally, the battle was won. Dr. Kelly asked a nurse to  (15)  the bill to her room．She was afraid to open it   (16)   she knew that it would  (17)  the rest of her life to pay it off. Finally she looked and read these words on the side of the bill:

“Paid in full with a glass of  (18)  .” (Signed) Dr. Howard Kelly.

    Tears of   (19)   flooded her eyes as she   (20)  silently: “Thank you, God. Your love has spread through human hearts and hands.’’