Ответ:

1. They have already finished their work.

2. They have already cooked a lunch.

3. She has already cleaned the room.

4. He has already finished his project.

5. They have already started the work.

6. She has already cooked dinner.

7. Already he has had a lunch. (не точно)

8. She has already bought a car.

9. The have already left.

10. He has just cooked a lunch.

11. They have just finished their work.

12. She has just came back.

13. She hasn't yet finished her work.

14. He hasn't yet came back.

15. They haven't yet cooked a lunch.

16. They haven't yet cleaned the flat.

17. She hasn't yet started her work.

18. He hasn't yet did his homework.

19. Have you already cooked a lunch?

20. Has he already did shopping?

21. Have they already cleaned the flat?

22. Has she already started the work?

23. Has he already finished his work?

Как-то так

Объяснение:

Место наречия already в предложении – между вспомогательным и основным глаголом, но иногда already может стоять в конце предложения.

В вопросах already ставится после конструкции have/has noun already.....

Наречие just в утверждениях обычно ставится между вспомогательным и главным глаголами.

В отрицаниях yet может стоять после вспомогательного глагола, но часто место yet – в конце предложения или вопроса.