Ответ:

2. The party was organised by my friends

My friends organised the party.

3. Bob and Steve broke the window.

THe window was broken by Bob and Steve.

4. The e-mails were sent by secretary.

The secretary sent the e-mails.

5. The robbers were caught by the police.

The police caught the robbers.

6. The reporter interviewed the actress.

The actress was interviewed by the reporter.