① He/she took first place in his/her first national competition.
② They took first place in their first national competition.
「全国大会に初出場初優勝した」
① He/she took first place in his/her first national competition.
※ take first place 優勝する
※ national competition 全国大会
② They took first place in their first national competition.
※ チームなどの場合、複数
アメリカ合衆国 
