“For” and “since” are used with perfect tenses to talk about events which began previous to the point of reference and continue until the point of reference. “For” is used to emphasize the amount of time something has been happening, and “since” is used to emphasize the time when the even began. Both can be used to talk about the same thing, but for different reasons. In the case of “for” the focus in on the length of time, and in the case of “since” it is about the beginning of it. “For” can also be used with the simple past to describe the duration of actions that ended in the past. However, since can only be used with perfect tenses.
Phrases for use with “for” and “since”:
|…ages/a long time||…last week/last year|
|…he quit his job in Boston (clause with simple past verb|
- Subject + Verb phrase in a perfect tense + here/noun form + (for + amount of time) OR (since + specific time or time phrase)