Look at these sentences.
(a) I graduated from high school last year. (b) I graduated high school last year. (C) I finished high school last year.
Which one would you use?
Most native speakers I know said they use (c). However, high school textbooks use (a). COCA says that (a) has 355 examples, (b) has 239 examples, and (c) has 355 examples.
Are these three used interchangeably?
Considering that students who graduate from the university are called graduate students, I think what is graduated from should be the university, not high school.
Do you have any ideas?