They're swimming.(对划线部分提问)

问题描述:

They're swimming.(对划线部分提问)

What are they doing?

划线是swimming.吧
答案:

【What are they doing ?】
他们正在做什么?
【Me YC真诚为你解答此题,若有疑问请及时追问,满意望及时选为满意回答】

划they:Who are swimming?/Who is swimming?
划swimming:What are they doing?