Questions & Answers about Відкрийте рот.
Because Відкрийте is an imperative form: it means open!
The ending -йте here marks:
- a command to more than one person, or
- a polite/formal command to one person.
So Відкрийте рот. is the polite/plural way to say Open your mouth.
The base verb is відкрити = to open.
The informal singular version is:
Відкрий рот.
Use this when speaking to:
- one friend,
- a child,
- someone you address with ти.
Use Відкрийте рот. for:
- one person formally (ви),
- or several people.