used to do过去常常做某事
He used to swim every day.他过去每天都游泳.(现在不是了)
be used to do被用来做某事,use sth to do的被动形式
Petroleum can be used to produce various chemical products.石油可用于生产多种化学产品
used to do过去常常做某事
He used to swim every day.他过去每天都游泳.(现在不是了)
be used to do被用来做某事,use sth to do的被动形式
Petroleum can be used to produce various chemical products.石油可用于生产多种化学产品