I know that "You decided" is simple past, but I've never ever seen this kind of construction until I listened it in a song (You did decide):
Pronoun + Simple Past(Past assistant did) + simple present
Then,
what is the difference? Does this construction really exit?
Best Answer
In simple sentences, we don't usually use the verb to do to indicate the tense(past/present). It only occurs in a question(interrogative)
However, you can use it in simple sentence for emphasis
EDIT: It also occurs in negative sentences