Choose the right verbs to complete the sentences.

Choose the correct option.

Do you see a flying saucer? I'm not sure, that [must|may|can't] be just an optical illusion.

This [must|may|can't] be Mike, he'll turn back only in a week!

That woman [must|may|can't] be a famous actress. I'm absolutely sure that she starred in a James Bond movie.

You [must|may|can't] be a winner of this race, you don't run fast enough.

Elsa [must|may|can't] become your friend. However, I'm not sure about it.

This picture [must|may|can't] be painted by Picasso. I saw it in a book of his works.