無冠詞で使う「普通名詞」

school と a/the school

生徒や教師が学校について話す場合は無冠詞
Do you walk to school?
We go to school by bus.

本来の目的以外で用いたり、形容詞句がつくと 冠詞がつく。
My parents went to the school to talk to the teacher.
She teaches Japanese at a school in Australia.