It was a small town 50 years ago. There wasn't/weren't a supermarket but there was/were a lot of small shops. There was/wasn't a circus then, but there wasn't/weren't many cars. There was/were small houses.

Ответ:

It was a small town 50 years ago. There wasn't a supermarket but there were a lot of small shops. There wasn't a circus then, but there weren't many cars. There were small houses.

Разберем каждое предложение:

• "There wasn't a supermarket" – так как supermarket в единственном числе, используем wasn't.
• "There were a lot of small shops" – так как shops во множественном числе, используем were.
• "There wasn't a circus" – так как circus в единственном числе, используем wasn't.
• "There weren't many cars" – так как cars во множественном числе, используем weren't.
• "There were small houses" – так как houses во множественном числе, используем were.

Ответ: It was a small town 50 years ago. There wasn't a supermarket but there were a lot of small shops. There wasn't a circus then, but there weren't many cars. There were small houses.