indirect speech / reported speech

He asked which umbrella was mine.
Note :
All verbs and verb-to-be should be changed to past tense because he has already asked, and you are just repeating what he has asked in the past.

He asked, "Which umbrella is yours?"
他問:那把雨傘是你的?



He asked me which umbrella was mine
他當時問我那把雨傘是我的.


引號 > Me
is > was
yours > mine

He asked me which umbrella was mine.

he asked which umbrella is mine.