(1) जब हम Point in time की बात करते है जैसे:- 8 o’clock, 4 A.M, 2nd October, May, Sunday, 2017, Yesterday, Morning & Evening Etc. तो वाक्य में “Since” का प्रयोग होता है।

Radha has been working since 5 am / 12:30 pm / 3 o’clock.
She has been studying since morning/evening/night/midnight.
Rohan has been working here since Diwali / Holi / Gandhi Jayanti.
They have been playing since today/yesterday.
(2) जब हम Duration of time की बात करते है जैसे:- 10 seconds, 30 minutes, 3 hours, 4 weeks, 6 months, 2 years, for a long, for a while & for many days & for many hours/days/months/years Etc. तो वाक्य में “For” का प्रयोग होता है।
He has been running for 3 hours / 2 days / one week.
The patient has not been speaking for 6 days.
Ravi has been living in Delhi for 8 months / 3 years / 2 decades.
It has been raining continuously for 2 weeks.