1

In an active sentence, the subject does the action (e.g., 'Shakespeare wrote Hamlet'). In a passive sentence, the focus shifts to the object receiving the action (e.g., 'Hamlet was written by Shakespeare').

2

We use the passive voice when the person doing the action is unknown, unimportant, or obvious from the context. To form the Present Simple passive, use 'am/is/are' + the past participle (Verb 3). For example, 'The office is cleaned every day.'

3

To form the Past Simple passive, use 'was/were' + the past participle. For example, 'The bridge was built in 1990.' If you want to say who did the action, use the word 'by' at the end of the sentence.