主句與從句的動作發(fā)生在不同的時間,這時主,從句謂語動詞的虛擬語氣形式因時間不同而不同,這叫做混郃條件句。 If you had asked him yesterday, you would know what to do now. (從句與過去事實相反,主句與現(xiàn)在事實相反。) If it had rained last night (過去), it would be very cold today (現(xiàn)在).