11. The young man (to introduce) to me only a couple of hours ago, but it seems to me that I've known him for years. 12. The rule explained by the teacher at the last lesson (to understand) by all of US. 13. The poem was so beautiful that it (to learn) by everybody. 14. I hope the invitation (to accept) by everybody. 15. The letter (to post) in half an hour. 16. It seems to me that music (to hear) from the next room. 17. Many houses (to burn) during the Great Fire of London. 18. His new book (to finish) next year. 19. Flowers (to sell) in shops and in the streets. 20. St. Petersburg (to found) in 1703.​

Ответ:

was introduced

was understood

was learned

will be accepted

will be posted

is being heard

were burned

will be finished

are sold

was founded

Объяснение:

вот