Say something has already happened
Combine もう with a past-tense verb to say something has already been done.
JLPTN5
もう + verb (past, 〜ました)mō + [verb past (~mashita)]
have already done ~
もう means 'already', and pairing it with a past-tense verb such as 〜ました confirms that an action is complete as of now. It often answers a question about whether something is finished, signalling 'yes, done'. This is the affirmative counterpart to まだ〜ていません, which says the action has not happened yet.
Tips and Common Traps
Hana· Key point
もう with a past verb is one of the most useful phrases when coordinating with people — もう着きました (I'm already here) saves a lot of explaining.