Tens of thousands of trees in the area in the past few years.A. have been plantedB. were

问题补充：

Tens of thousands of trees in the area in the past few years.

A. have been planted

B. were planted

C. have planted

D. had planted

答案：

(答案→)A. have been planted

B. were planted

C. have planted

D. had planted

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