Did indeed: stressed có before the verb

Có before a verb, said with a little stress, insists that something really happens or happened: Em có đi học mà! I did go to class! It's how you answer when someone doubts you, like English "I did" or "I do".

It usually comes up when you put someone right: Hôm qua em có gọi cho anh, mà anh không nghe máy. I did call you yesterday, but you didn't pick up. Mà at the end often goes with it, adding "I'm telling you": Chị có nói với anh rồi mà! I did tell you!

You know có + noun as "have" (có xe) and có … không for questions. Here có comes before a verb in a statement. It never means "have to"; that's phải. Out of the blue, Tôi có thích phở sounds as if someone had doubted it; the plain statement is Tôi thích phở.

For the opposite, "but I didn't!", use có … đâu: Em có nói đâu! I never said that!

In the South you'll also hear không có before a verb: Em không có đi. I didn't go. It's common in Saigon speech, and can sound a little firmer than plain không.