Краткое пояснение:
Правило: Используем наречия already, yet, just, ever, never для передачи различных смыслов в настоящем совершенном времени (Present Perfect).
Ответ:
- She has already been to Buckingham Palace twice.
- They haven't learnt to snorkel yet, so they can't come with us.
- We have just finished school for the day.
- If you have not packed your suitcase ever, then I will do it for you.
- I have never been this happy.