This question already has an answer here:
In sentences like "Two questions are what I wanted to ask", should I treat the subject, "Two questions", as singular or plural?
It seems more natural to treat it as plural. But when I reverse the subjects I'll need to use the singular form instead : "What I wanted to ask is two questions" and this doesn't look very natural.
Does the same apply to chronological sentences like "5 months is/are what I have left to finish this project of mine"?