问题补充：
The Changjiang River has been polluted badly and is not good ．
A. to swim it
B. to be swum in
C. to swim in it
D. to swim in
答案：
A. to swim it
B. to be swum in
C. to swim in it
(答案→)D. to swim in
解析：考查不定式的用法。swim是不及物动词，应该是swim in the river；介词in不能省略，排除A、C；sth. is +形容词+to do sth.用不定式的主动形式表被动含义。故选D。
