Good question! 1) I haven't seen him since 2019. = You still have not seen him. 2) I I hadn't seen him since 2019. = You recently saw him, but the previous time was in 2019.

Hello Mahmoud I haven't seen him since 2019. Meaning.....Since 2019 to the present time, you have not seen him This is the Present Perfect tense I hadn't seen him since 2019 This is the Past Perfect tense, however, it is not used this way. The past perfect tense is used to indicate that an action took place once or multiple times before another point in the past. Example: I had not seen him before he left for London. I hope that this helps :)

1. The statement is still true until today. 2. I'm not sure if since can be used in the past perfect tense but the statement happened in the past and therefore may no longer be true as of this timing. In past perfect, the timeframe was in the past and should ended in the past. Hope it makes sense.