Для преобразования предложений в пассивный залог, используйте соответствующую форму глагола "to be" и причастие II (past participle) основного глагола. Вот решения:
Moscow University has been visited by millions of people during the past few years.
The lectures will be attended by all of the students tomorrow.
Art is painted by all of us every day.
The next competition will be won by our team.
The bag was brought to you two days ago.
The young man will be introduced to me next Tuesday.
The letter has already been forgotten by everyone.
The painting is being shown at the moment.
The house is painted by boys every day.
The flowers were watered by me yesterday.