有一读者问： 有这样三个句子：
(1)Wang Bing is leaving the USA after two years.
(2)Yang Pei is leaving Australia after two years.
(3)Peter and Bill are leaving China after three years.
这里为何不用in而用after?
这里既可用in亦可用after。但二者是有区别的。in two years可意为“两年之后”，亦可意为“两年之内”。而after two years则只有一个意思，即“两年之后”。
