鑒別虛擬語氣主要看的是時態(tài).
與現(xiàn)在事實(shí)相反,從句用一般過去時,其中be動詞統(tǒng)一用were,主句用would或was/were going to加動詞原形,也就是過去將來時.比如,if I were you, i would not agree with it.
與過去事實(shí)相反,從句用過去完成時,主句用would或was/were going to加完成時,也就是過去將來完成時.比如,if he had accepted my advice, he would not have failed the exam.
與將來事實(shí)相反時,條件從句的時態(tài)為一般過去時/（were+不定式）/（should+動詞原形）,比如,if you succeeded, I would give you a surprise.
與現(xiàn)在事實(shí)相反和將來事實(shí)相反的時態(tài)是很相近的,要看意思.
if...will...是條件狀語從句,是可能發(fā)生,if后面用現(xiàn)在時態(tài)表示將來.