(11)People used to believe that the earth was flat.
过去，人们总以为地球是扁平的。(现在已不再这样认为)
(12)He would go to the park as soon as he was free.
过去，他一有空就去公园。(现在有可能再去)
注意：used to的否定式和疑问句:
(13)过去我不喜欢歌剧。
I used not to like opera.
I usedn't to like opera.
I didn't use to like opera.
(14)过去你喜欢歌剧吗?
used you to like opera?
Did you use to like opera?
(15)Didn't you use to like opera? 你过去不喜欢歌剧吗?
(16)You used to like opera, didn't you? 你过去喜欢歌剧，是吗?
(17)There used to be a church here， usedn't there? 过去这里有座教堂，是不是?