问题
选择题
We _____ in this pool when we were young, but now it _____ fish.
A．are used to swim; used to keep
B．are used to swimming; used to keep
C．used to swimming; is used to keep
D．used to swim; is used for keeping
答案
答案：D
题目分析：be used for sth被用于某事;used to do sth过去常常做某事.句意：当我小的时候，我常常在这个池子里游泳，但是现在它被用来养鱼。
点评：used to用法比较固定，需要注意use还可以作为被动语态使用，sth be used to do sth某物被用来做某事。