问题
选择题
If it __________for the snow, we ___________the mountain yesterday.
A．were not; could have climbed
B．were not; could climb
C．had not been; could have climbed
D．had not been; could climb
答案
答案：C
题目分析：句意：假如天气昨天没有下雪，我们就已经爬上了那座山峰。if引导的从句对过去情况的虚拟推测，从句用had done，主句用would/should/could+have +done,故选C
点评：if的虚拟语气非常重要，简要概括如下：1、表示与现 在事实相反的情况，从句：If主语+过去时(Be动词用were)；主句：主语+should/would/could/might+do： 2、表示与过去事实相反的情况，从句：If主语+had+done；主句：主语+should/would/could/might+have done 3、表示对将来情况的主观推测，从句：①if+主语+were to do②if+主语+should+do ③if+主语+did（动词过去式）/were ；主句：主语+should/would/could/might+do