Did they study at home与Were they study at home 的区别,应该用哪个?

Did they study at home与Were they study at home 的区别,应该用哪个?
Did they study at home与Were they study at home 的区别,应该用哪个?
发错了是Did they stay at home与Were they stay at home

Did they stay at home ?表达正确,使用这个
Were they stay at home?这是错误的.句子中出现了were 和stay 两个谓语动词
再问： 请问下那did 也是助动词啊，为什么正确？
再答： did 之所以叫做助动词，是因为和实义动词一起构成谓语动词。所以在疑问句和否定句中通常都有 do/don't,did/didn't+动词的形式 而be动词（指am，is ，are）和实义动词在一个句子的时候通常构成进行时或者被动语态，实义动词不可能使用原形。例如： I am reading a book.【be+动词ing构成现在进行时态】 I was told to do that .【be +动词ed，即过去分词构成被动语态】 Were they stay at home？错误。可以改成 Were they 【staying】 at home？构成过去进行时，他们当时在家吗？ 不懂继续追问