英文 英文 英文 英文 英文 英文

1 及 3為現在進行式; 2為現在式

are you studying in secondary school?
(你是否正在在中學學習?)
do you study in secondary school?
(你有在中學學習嗎?)
is he studying in secondary school?
(他是否正在在中學學習?)

以上三句都是正確的句子, 問題是你究竟想表達(問)什麼

In fact, all of them are correct. However, sentence one and sentence three are usually used in letters and conversation.

They are all correct.