He is English. Do you need to add one or one?

If English students fall behind. There must be an article in front, right?

There must be an article about this. Let me analyze it for you:

English is a dispensable thing, because English represents a kind of people. If "Englishman" has only 1 person, an should be added before it. If it represents a class of people, that is, "the British", then there is no need to add an article.

Student is a noun without plural, which means 1 person, so the article an should be added.

Good luck!