這是虛擬語氣的固定用法.虛擬語氣對現(xiàn)在的虛擬有兩種,【實(shí)意動詞用過去式,be動詞用were（不能用was）】.這兩種分別舉例如下：
If he finished his homework, I would be so surprised. 如果他現(xiàn)在完成了作業(yè),我會很吃驚的.
If I were you , i would go to the cinema. 如果我是你,我就去電影院.那決不能用was了吧是的，不能用was，不管主語是什么，只要是be動詞，都要用were。