在表示从现在算起或从过去某个时间点算起的一段时间的末尾(即多少时间后)这一意思时,可以用 in three days (注意:不是 in three days time)结构,也可以用 in three days’ time 结构,二者没有什么区别。但是,如果表示做某事所经历的时间长度时,可以用in three days 结构,不能用 in three days’ time 结构。例如:
(1) She is going up to London in three days’ time. (= She is going up to London in three days.) 她打算三天后去伦敦。
(2) The bull-fight was to commence in twenty minutes. (= The bull-fight was to commence in twenty minutes’ time.) 斗牛将在20分钟后开始。
(3) The bird covered the distance in three minutes. (不能说:The bird covered the distance in three minutes's time. )