ad. （常用於現在完成式或過去完成式）
- 此後；從那時到現在She left school three years ago and has worked as a nurse ever since.
她三年前畢業，從那時起便一直當護士。
- 之前，以前
prep.
- （常用於現在完成式或過去完成式）自……以來，從……至今I haven't heard from him since last year.
我自去年以來未曾收到過他的信。
conj.
- （常用於現在完成式或過去完成式）自……以來，從……至今It's been ten years since they married.
他們結婚到現在已經十年了。
She has been living a hard life since her husband died.自從丈夫死後，她一直過著艱苦的生活。
- 既然；因為，由於He must have taken the book since it isn't here.
他一定是把書拿走了，因為書已不在這裡了。
Since it is so hot, let's go swimming.既然天氣這麼熱，我們去游泳吧。