他们在干什么用英文怎么说说

"What are they doing?" is a common way to ask about someone's actions in Engpsh. The phrase is straightforward and widely used in both spoken and written Engpsh.

Example:

"What are they doing?"
"I wonder what they're up to."

中文翻译：

"他们在干什么？"
"我想知道他们正在做什么。"