Question

the letter (send)___yesterday
the Bolshoi Theatre (build)___in1776
this picture (paint)____by a well-know artist in 1890
Moscow (found)___in 1147
Yuri Gagarin (send)__to space on the 12th of April, 1961

Answer 1

Это все страдательный залог, т.е. was/were + глагол во II форме (т.к. здесь Past Simple везде).
1) was sent
2) was built
3) was painted
4) was founded
5) was sent

Answer 2

The letter was sent yesterday.
The Bolshoi Theatre was built in1776.
This picture was painted by a well-know artist in 1890.
Moscow was founded in 1147.
Yuri Gagarin was sent to space on the 12th of April, 1961.