16.3 混合條件句

　 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，這叫做混合條件句。
　　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).