if引导的虚拟条件句【教学类别】

与现在事实相反：与现在事实相反：if条件句用一般过去时（动词be用were），主句用would(should/could/might)+动词原形、带、带if if的虚拟条件句的虚拟条件句与将来事实相反与将来事实相反(推测将来推测将来)：if 条件句中用过去时，或should/were to+动词原形，主句用would(should/could/might)+动词原形。与过去事实相反：与过去事实相反：if 条件句中用过去完成时，主句用would（should/could/might）+have+过去分词。条件从句条件从句结果主句结果主句与现在事实相反与现在事实相反If +主语主语+过去式过去式 主语主语+would/should/could/might do 与将来事实相反与将来事实相反If+主语主语+过去式过去式主语主语+would/should/could/might dowere to do/should/could do)与过去事实相反与过去事实相反If+主语主语+had+过去分词过去分词主语主语+would/should/could/might have doneIf引导虚拟条件句中的谓语动词变化 He must have had an accident,or he then_.Awould have been here Bshould be here Chad to be here Dwould be there答案为A。or 在这里隐含了与过去事实相反的虚拟语气，表示if he had not had an accident,所以其后的主句用would have done 而不用其它的。