Plain form (or noun / na-adj root) + かどうか

Meaning: whether or not
Cấu trúc (Formation): V / i-adj plain + かどうか (来るかどうか, 難しいかどうか). Noun / na-adj root + かどうか, NO だ (学生かどうか, 静かかどうか).
Độ trang trọng: neutral