My mother was the most warm hearted person I have ever known => I have...... The police started looking for him two months ago => For two months now the.....

`1,` I have never known anyone as warm-hearted as my mother.

- This is the Superlative (…est/ most ADJ N) S +have/has+P2

->  S +have/ has + never + P2+ such a/an+ ADJ+ N 

`2,`For two months now, the police have been looking for him.

- started/began + to V / Ving = have V3 / have been Ving : bắt đầu làm việc gì