が with skill predicates
grammar9 sentences
With predicates of skill, ability, or aptitude (上手, 下手, 得意, 苦手, 流暢), the area or object is marked with が, not を — 英語が上手だ ('skilled at English'), 数学が苦手だ ('bad at math'). Grammatically が marks the subject of the stative predicate; structurally 'X が Y だ' = 'X is the area in which Y holds.' Part of the broader family of stative predicates (好き, 嫌い, 必要, 分かる, 欲しい) that take their logical object with が.
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