This is the only way that I can think of the problem of water waste in urban areas.A. set

问题补充：

This is the only way that I can think of the problem of water waste in urban areas.

A. settling

B. to settle

C. settle

D. settled

答案：

A. settling

(答案→)B. to settle

C. settle

D. settled

解析：考查不定式做定语：句意：这是我能想到的唯一的解决都市地区水浪费的问题的方法。这里that I can think of是定语从句，所以横线部分是定语，修饰the way，the way to do sth/of doing sth“做…的方法”，选B。