the apartment block is old and dangerous .It should be pulled down.为什么用pulled 而不是 pull
问题描述：
the apartment block is old and dangerous .It should be pulled down.为什么用pulled 而不是 pull
答
被动式.东西被人拉下来加ed 的不是过去式么？被动语态就是BE + 动词过去式哦，明白了，谢谢