You can hardly imagine the once clear canal _____ so seriously polluted that no fish can live in it.

题目简介

You can hardly imagine the once clear canal _____ so seriously polluted that no fish can live in it.

题目详情

You can hardly imagine the once clear canal _____ so seriously polluted that no fish can live in it.
[     ]
A. have become  
B. having become  
C. to have become  
D. to become
题型:单选题难度:中档来源:同步题

答案

B

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