抽烟4年了: ...since the habit of my smoking was developed. 戒烟4年了:...since the last chance of my smoking.
-redjunk(toy);
2009-4-19{211}(#5204646@0)
that is it. 'Since' is an adverb, just introducing one time reference point for the present perfect tense in the first part of the sentence. It says nothing about whether the habit of smoking continues or not.
i have been smoking for 4 years...(intend to continue smoking)...my understanding.
-wince(玄色);
2009-4-20(#5208145@0)
戒烟4年了（正解！）：four years ago he smoked, but he hasn't smoked at all after that time (during the past four years).
-redjunk(toy);
2009-4-21(#5208473@0)
我感到这个句子可以有两种解释：It has been four years since I began to smoke. / It has been four years since I stopped smoking. 如果是第一种，那就是：我抽烟已经4年了。如果是第二种，那就是：我戒烟已经4年了。
-lilianali51(lilianali51);
2009-4-21(#5209034@0)
让偶想起了这歌的第一句歌词。。。It’s been seven hours and fifteen days since you take your 。。。
-stalker(为了枯干的灌水);
2009-4-19{441}(#5204697@0)