used to
modal
v (neg 否定式 used not to, contracted form 缩约式 usedn´t to, usen´t to ) (expressing a frequent or continuous action in the past; in questions and negative sentences usu with did 表达过去经常的或持续的行为, 在疑问句和否定句中通常与did连用)
I used to live in London. 我过去一直住在伦敦.
Life here is much easier than it used to be. 如今在此地生活比起从前可舒服多了.
You used to smoke a pipe, didn´t you? 你过去一向是抽烟斗的, 对不对?