The water in this river is harmful because It’s a river.A. pollution B. polluted C. has p

问题补充：

The water in this river is harmful because It’s a river.

A. pollution

B. polluted

C. has polluted

D. pollutes

答案：

A. pollution

(答案→)B. polluted

C. has polluted

D. pollutes

解析：由横线后的“river”可知此空修饰名词，故应为形容词，因为A是名词，CD为动词，故选B。