Необходимо поставить предложения в пассивный залог 1. don't disturb him. he's dictating a very important letter to his secretary. 2. she was describing the accident to passers-by when the police arrived. 3. oh, dear! she's been waiting for me for a quarter of an hour already. 4. what are they looking for? 5. some stranger offered his help when i fell down in the street. 6. when did he write this book? 7. he speaks in such a low voice that nobody ever listens to him. 8. mr. brown is buying a new car. 9. every woman is pleased when somebody pays her a compliment. 10. they haven't bought anything new lately.

Как то так..
1.  Very important letter is being dictated by him  to his secretary.
2. the accident  was being described by her  to passers-by when the police arrived.
3. I have been being waited by her for a quarter of an hour already.
4. нет пассивной формы
5. I was  offered some stranger's help  when I fell down in the street.
6. When was this book written by him? 
7. He is not listened by anybody, because He speaks in such a low voice
8. a new car is being bought by Mr. Brown  .
9. Every woman is pleased when she is paid by a compliment.
10. Nothing has been bought by Them lately.