1. передайте следующие предложения в пассивном залоге. 1) he sent for the doctor an hour ago. 2) they will write a letter tomorrow. 3) they built a new hospital last year. 4) she is reading a book at the moment.

The letter will be written tomorrow.
A new hospital was built last year.
A book is being read at the moment.

Первое не уверена...
Может быть, так:
The doctor was sent for an hour ago.