Ответ:

1. He went to the country last summer.

• Interrogative sentence: Did he go to the country last summer?
• General question: Where did he go last summer?
• Alternative question: Did he stay in the city last summer?

1. We were dancing in the hall.

• Interrogative sentence: Were we dancing in the hall?
• General question: What were we doing in the hall?
• Alternative question: Were we singing in the hall?

1. I have seen Peter at the theatre.

• Interrogative sentence: Have I seen Peter at the theatre?
• General question: Who have I seen at the theatre?
• Alternative question: Have I seen Peter at the cinema?

1. They will be planning to have a holiday soon.

• Interrogative sentence: Will they be planning to have a holiday soon?
• General question: What are they planning to do soon?
• Alternative question: Will they be working soon instead of having a holiday?