leave school

finish one's education

毕业；离校，辍学

he left school at 16.

他16岁时毕业离校。

of (或 from) the old school

he left school at 16.

他16岁时毕业离校。

the school of hard knocks

he left school at 16.

他16岁时毕业离校。

school of thought

a particular way of thinking, especially one not followed by the speaker

（尤指说话人不赞同的）思潮

there is a school of thought that says 1960s office blocks should be refurbished as residential accommodation.

有一种思潮认为60年代的办公街区应重新装修用作住宅。