单选题 Once environmental damage , it takes many years for the system to recover.
  • A) had done
  • B) is done
  • C) is to do
  • D) does


【正确答案】 B
【答案解析】[考点] 被动语态
[解析] 主语environmental damage与谓语“做”之间是被动关系，所以用is done。
[避错] had done为过去完成时形式；is to do为一般将来时形式；does为一般现在时形式，都不包含被动的含义。