【 】are they【 】about?they are talking about Lucy birthday party

问题描述:

【 】are they【 】about?they are talking about Lucy birthday party

What are they talking about?
因为about为介词,后缺宾语,所以用what提问
用现在进行时是因为这是他们正在讨论的,提问的时候正在讨论,多用进行时,可作句型使用