▲the high school（指具体的某所中学）

she teaches at the local high school. 她在当地中学当老师。

Each student at the high school has a locker. 这所中学每位学生都有锁柜。

▲high school（指在中学求学）

She learned some American history in high school. 她在中学学了点美国历史。

She took my advice and did not drop out of high school. 她听从我的建议，没有从高中退学。

It was the summer before his junior year in high school. 那是他升入高三前的那个夏天。