Past Continuous Tense

Active sentences in the past continuous tense have the following structure:
Subject + was/were + -ing form of the verb + object
Passive sentences in the past continuous tense have the following structure:
Object of the active sentence + was/were + being + past participle form of the verb + by + subject of the active sentence

Examples are given below:

Active: She was writing a novel.
Passive: A novel was being written by her.
Active: They were saying their prayers.
Passive: Their prayers were being said by them.
Active: He was giving a lecture.
Passive: A lecture was being given by him.

Changing a negative sentence into the passive

Active: She was not preparing dinner.
Passive: Dinner was not being prepared by her.
Active: He was not making a speech.
Passive: A speech was not being made by him.

Changing an interrogative sentence into the passive

Passive forms of these sentences begin with was or were. If the active sentence begins with a question word, the passive sentence will also begin with a question word.

Active: Is she writing a letter?
Passive: Is a letter being written by her?
Active: Why were you cheating me?
Passive: Why was I being cheated by you?
Active: Which book were you reading?
Passive: Which book was being read by you?
Active: Why was she beating the child?
Passive: Why was the child being beaten by her?
Active: For what were you making such a noise?
Passive: For what was such a noise being made by you?

Past perfect tense

Active voice: Subject + had + past participle form of the verb + object
Passive voice: Object of the active sentence + had + been + past participle form of the verb + by + subject of the active sentence

Active: I had never experienced such difficulty.
Passive: Such difficulty had never been experienced by me.
Active: I had not listened to him.
Passive: He had not been listened to by me.
Active: I had finished my work.
Passive: My work had been finished by me.
Active: I had written a letter.
Passive: A letter had been written by me.
Active: He had given a lecture.
Passive: A lecture had been given by him.

Changing an interrogative sentence into the passive

Active: Had she invited them?
Passive: Had they been invited by her?
Active: Had she prepared dinner?
Passive: Had dinner been prepared by her?
Active: Had he given a lecture?
Passive: Had a lecture been given by him?