Show me a list of singular and plural form of tenses
Since and for, both prepositions are used to express time.
Since is used to express the starting point of time, when an activity started, till the present time.
1. Meetu and Muthu have known each other since childhood.
2. Steve Jobs has been serving Apple as its CEO since 1997.
3. She has been on her official trip since last Monday.
4. They are good friends since the day they met.
For is used to express a fixed time duration of an activity.
1. The World War II lasted for six years.
2. Amrita’s trip to Switzerland was for a week.
3. We worked in the office today for over 10 hours.
4. I have known Mr. Hancock living in New York City for two decades.
Hope this helps.
All the best!