翻译参考答案如下：

1. They had a ball, but I was not in it.

2. We were having a ball when we toured Beijing.

3. We are happy to hear you having a ball.

4. We are having a ball, but the sound troubles my neighbours.

5. No one danced until Charles and Mary broke the ice by going out on the floor;from then on, everybody had a ball.

6. I'm glad that you are having a ball, but you are making too much noise.