否定句：There weren't about nine hundred people at the concert.
一般疑问句：Were there about nine hundred people at the concert?
括号部分提问 How many people were there at the concert 请问那个回答是怎么样，麻烦你补充，谢谢划线提问的 回答：There were about nine hundred people at the concert .


如果是一般疑问句的回答就是：
肯定回答：Yes , there were.
否定回答： No, there weren't.