Expressing duration of inaction
Saying how long you have not done something is not difficult, but the word order is different from the regular pattern for expressing duration. If there's a consistent keyword in this pattern, it's going to be 没 (méi), since it almost always plays a role.
Subj. + (已经 +) Duration + 没 + Verb + 了
So now the duration comes right after the subject and 了 is at the end of the sentence. The verb has to be negated with 没, as the action hasn't happened.
Note that 已经 can be omitted.
- 他们 已经 两 天 没 吃 东西 了 。They haven't eating anything for two days already.
- 我们 已经 十 年 没 见 了。We haven't seen each other for ten years already.
- 他 已经 一 个 星期 没 洗澡 了 。He has already gone a whole week without showering.
- 你 多 长 时间 没 刮 胡子 了 ？How long has it been since you last shaved?
- 她 半 个 月 没 出门 了 。It's been half a month since she's left the house.
- 你们 多久 没 回家 了 ？How long has it been since you returned home?
- 你 多久 没 休假 了 ？How long has it been since your last vacation?
- 买 吧 ，你 已经 一 年 多 没 买 新 衣服 了 。Just buy it. It's been more than one year since you last bought new clothes.
- 你 好像 很久 没 这么 开心 了 。It seems like it's been a long time since you were this happy.
In English, we may say something like, "I haven't eaten since 9:00 this morning" or "I haven't been to China since the year 2000." Note that the Chinese do not tend to say somebody hasn't done something since a certain point in time. Instead, you should either express it as a duration of time that one hasn't done something (as in the above examples), or you can say "the last time somebody did something was [a certain point in time]."
- 我 已经 十 年 没 来 中国 了 。It's been 10 years since I came to China last.
- 我 上次 来 中国 是 2010 年 。The last time I came to China was 2010.