I want to ask the students what they are doing
句意：我想问（知道）学生们正在干什么
分析：这是一句宾语从句,省略I want to ask the students （that）what they are doing中的that,很容易让人误认为定语从句,注意审题：它的先行词不是what!
翻译：请告诉我你在干什么?我想要知道汤姆在跟谁说话
回答：Please tell me what are you doing(now)?
I want to know who is spenking to Tom?