Inspired by a past-perfect vs. present-perfect online test:
They were angry because they had waited for too long.
and
They were angry because they had been waiting for too long.
Are both options grammatical?
If yes, what is the difference in meaning?
The second options seems to be more widespread, according to a quick Google search.
Is it because with had waited, the process of waiting might have ended before them becoming angry, and so there is a gap between their "waiting" stopped and their "angriness" started?
Best Answer
Say they waited from 10:00 to 11:00 am. It is now 1:00. If you were saying they were angry at 11:00 while still waiting you could use either form but the second is better because it is more clear. If you were saying they were angry at noon--after the waiting but still in the past--then you would use the first form.