This question already has an answer here:
- “did shoot” vs “shot” 2 answers
What is the correct syntax:
- "Which browsers do support this?"
- "Which browsers support this?"
marked as duplicate by RegDwigнt♦ Feb 6 '13 at 11:25
This question was marked as an exact duplicate of an existing question.
The do form contrasts with a previous statement:
It's not restricted to the interrogative. It's one case of do-support.