I.单项填空
A young man, while traveling through a desert, came across a spring of clear water. 1. ______ water was sweet. He filled his leather container so that he could bring some back to an elder 2.________ had been his teacher. After a four-day journey, the young man 3._________ (present) the water to the old man. His teacher took a deep drink, smiled 4._______ (warm), and thanked his student very much for the sweet water. The young man went home 5.________ a happy heart.
