For vs Since - Hard Exercises

Advanced for and since questions test formal time phrases, past perfect contexts, and clauses where the starting point is less obvious. Use for with measured or approximate duration: for much of her career, for the best part of a decade, for several consecutive months. Use since with a point, event, appointment, decision, or historical marker: since the merger, since records began. The phrases may be long, but they still work as duration or starting-point signals.

The rule also works with past perfect. "They had waited for three hours" gives duration before a past moment. "They had not spoken since the argument" gives the starting event before that past moment. Formal writing often compresses a starting event into a noun phrase, such as since her appointment or since assuming office. Decide whether the phrase measures a stretch of time or identifies the point where the situation began. That distinction also helps with academic, legal, and news-style sentences.