高等继续教育 / 专科英语I
正确率：100%
题型描述: 单选题
Each year we waste tons of paper, and ＿＿＿＿＿＿＿＿ for many years.
A.does so
B.had done so
C.have done so
D.did so
Each year we waste tons of paper, and ＿＿＿＿＿＿＿＿ for many years.
A.does so
B.had done so
C.have done so
D.did so
参考答案：
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