if引导的条件状语从句主从语句能都是过去时吗?跟一般的从句一般现在时主句一般将来时的形式有什么区

不可以。If条件句的几种用法及区分见下真实条件句真实条件句用于陈述语气,假设的情况可能发生。表示将来时,主句是将来从句是现在,记住‘主将从现’。非真实条件句表示对将来的假想,是不可能发生的,如果对将来的虚拟,从句一般过去时。需要多做些题目来巩固。如果有疑问可以给我发短信。[解题过程]一、真实条件句 真实条件句用于陈述语气,假设的情况可能发生,其中 if 是如果的意思。时态关系句型：条件从句 主句一般现在时 shall/will + 动词原形If he comes,he will bring his violin。注意：1） 在真实条件句中,主句不能用be going to表示将来,该用shall,will。(错) If you leave now,you are never going to regret it。(对) If you leave now,you will never regret it。2） 表示真理时,主句谓语动词便不用shall (will) +动词原形,而直接用一般现在时的动词形式。二、非真实条件句 1）时态：可以表示过去,现在和将来的情况。它的基本特点是时态退后。a。同现在事实相反的假设。句型 ：条件从句 主句 一般过去时 should( would) +动词原形If they were here,they would help you。b。表示于过去事实相反的假设。句型：条件从句 主句 过去完成时 should(would) have+ 过去分词If she had worked harder,she would have succeeded。The rice would not have been burnt if you had been more careful。If my lawyer had been here last Saturday,he would have prevented me from going。If he had come yesterday,I should / would have told him about it。含义：He did not come yesterday,so I did not tell him about it。If he had not been ill and missed many classes,he would have made greater progress。含义：He was ill and missed many lessons,so he did not make greater progress。c。表示对将来的假想句型：条件从句 主句一般过去时 should+ 动词原形were+ 不定式 would + 动词原形should+ 动词原形If you succeeded,everything would be all right。If you should succeed,everything would be all right。If you were to succeed,everything would be all right。