Read these sentences and change them into general questions. Don’t forget about question marks.

1. She was reading a book at 4 o’clock yesterday.

2. They were swimming in the pool at 10 am yesterday.

3. Millie was listening to music at 8 pm yesterday.

Sure, here's a step-by-step explanation of how to change these sentences into general questions:

1. The original sentence is: "She was reading a book at 4 o'clock yesterday."
To make it a general question, we need to switch the order of the subject ("she") and the past tense form of the verb ("was reading"). Also, we need to add a question mark at the end. The revised question is: "Was she reading a book at 4 o'clock yesterday?"

2. The original sentence is: "They were swimming in the pool at 10 am yesterday."
To change it into a general question, we swap the subject ("they") and the past tense form of the verb ("were swimming"). Additionally, we include a question mark at the end. The revised question is: "Were they swimming in the pool at 10 am yesterday?"

3. The original sentence is: "Millie was listening to music at 8 pm yesterday."
To turn it into a general question, we exchange the subject ("Millie") and the past tense form of the verb ("was listening"). Lastly, we add a question mark. The revised question becomes: "Was Millie listening to music at 8 pm yesterday?"

By following these steps, we transformed the original sentences into general questions.