问题补充：
Some people waste too much water. They don’t believe that it cansome day.
A. keep out
B. run out
C. be run out
D. run out of
答案：
A. keep out
(答案→)B. run out
C. be run out
D. run out of
解析：考查固定短语。A“不让进入”；B“用光”；D“用光......”。句意“一些人浪费太多水了，他们不相信有一天睡会用完。”run out没有被动形式。故选B。
