I have a question regarding the future perfect tense and which prepositions go with it. Understandably, by, for, and in work very well with the future perfect.
By friday, I will have been working here for one year.
In two years, I will have worked here for two years.
However, my question is whether or not since is usable with the future perfect.
"Do you want to go out tonight?"
"Nah, I'll have been working since 9 AM. I'm going to be dead tired."
My guess is that this is usable as an approximation. I'll have been working here since May for example. Swan and Cambridge offer no solution for this. My question is: is this possible?
Best Answer
I can certainly understand the Future Perfect Progressive being used like that.
It's because our grammar textbooks traditionally just concern themselves with the point in the future (by, when etc.) for Future Perfect and Future Perfect Progressive. But in your example, the time in the future has already been mentioned: "(at some point) tonight".
So it makes sense for the speaker to just add the starting point of the action, which was unclear in the situation. Either this or the perfectly acceptable period of time: "for such number of hours."
We make sentences like: "I'll have been working for 6 hours," right? So, I think we can mention the starting point instead.