Certain prepositions signal which perfect tense to use
Single point in time: Continuous time:
by, in (used either in past or future) since/from/for
- Marie has developed four major products since (not from) the beginning of this year.
- The company has been enjoying a tax holiday since (not from) 1990.
- Marcus has worked at BART for (not since) twelve years.
- The relationship with Lloyd’s Bank was established by (not since) 1991. (simple past (passive voice); a single point in time)
- The relationship with Lloyd’s Bank started in (not since) 1972 (simple past; a single point in time)
1. Mr. Simon has been our customer (from, since) 1992.
2. All capital expenses are frozen (from, since) today through the end of the second quarter.
3. Regina has been developing our procedures manual (since, by) March.