"years old"と"year-old"

・「…は~歳です」は[主語+be+~years old]で表す。

[正]He is six years old.
[誤]He is six-year-old.

・名詞を修飾するときには、形容詞の"-year-old"が使われる。

[正]He is a six-year-old boy.
[誤]He is a six years old boy.

・"-year-old"は名詞としても使われる。

[正]He is a six-year-old.
[正]Our six-year-old is at school now.

"years old"と"year-old"の関連項目