问题
选择题
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
答案
答案：B
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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
答案：B