Present perfect vs simple past

Dear teachers,

Please read:

Yesterday was one of the coldest day that I have known.

1/I don’t know the reason why the present perfect is used in this sentence. Please tell me this reason.

2/ If I write:
Yesterday was one of the coldest day that I knew.

Is it correct? If not (or yes), please tell me the reason.


Hi Quoc

No 1 is correct becacuse you still know

No 2 would be correct if for example:
“He was a person I knew while at school, be I don’t know him now”.
If I still knew him I would say: “he is a person I have known since I was at school”.

The present perfect is used here because there is a relationship with now. You are still alive, and it’s possible for you to experience more cold days. However, in your whole life up to now, this has been one of the coldest days in your experience.

You can use this if you are dead and will never experience another cold day. If you are still alive, you need to use the present perfect, because the simple past is for finished times.