Ответ:21. Jack is not sure if he will be in London next week.
22. .If he go to London next week he will meet his cousin Mary.
23. If you don`t change your plans for the coming summer, i`ll go to the sea with you.
24. I don`t know when i will watch film but i really want to do it.
25. Please tell me when you will be able to come and see us.
Объяснение:
Во всех предложениях будущее время , значит мы везде ставим "will" . Но в 23 предложении у нас условное придложение, значит после if у нас Present Simple