完形填空

　　An old man had been hired many years ago by a town council(委员会)to clear away the wastes from the pools up in the mountain that fed the clear spring flowing through their town．　　1　　 faithful, silent work every day, he cleaned the hills, removed the 　　2　　 and branches, and wiped away the dirt that would otherwise 　　3　　 and pollute the clear flow of water．

　　By and by, the town became a(n)　　4　　 attraction for tourists．Swans floated along the 　　5　　 spring．The mill wheels(水车)set up near the water 　　6　　 day and night and farmlands were naturally 　　7　　．The beautiful view from the restaurants was beyond 　　8　　．

　　Years passed．One evening the town council 　　9　　 for its meeting．A man's eye noticed the salary 　　10　　 to the keeper of the spring．He said, “Why do we 　　11　　 the old man on year after year?He isn't necessary any longer!” They all agreed to 　　12　　 the old man's job．

　　For several weeks nothing changed．By early 　　13　　 the trees began to shed their leaves．Small 　　14　　 broke off and fell into the pools, blocking the rushing flow of sparkling water．One afternoon 　　15　　 noticed brown color in the spring．Some days later, the water was much 　　16　　 and more wastes covered the water and a kind of bad 　　17　　 was given off．The mill wheels moved very slowly, and finally 　　18　　．Swans left and so did the tourists．The dirty water 　　19　　 into the town．

　　　　20　　, the council called a special meeting．Realizing their mistakes, they hired back the old man and within a few months the river of life began to clear up．