虚拟预期在条件句中的应用：
1： If i were you , i would make better use of time at school.
如果我是你，我会更好地利用在学校的时间。
2：If you had taken your teacher’s advice ,you wouldn’t have failed in the exam .
如果你早听老师的话，考试就不会不及格。
3：If it should rain ,we would change our plan.
万一下雨的话，我们就改变计划。
用法
条件从句的谓语动词 主句的谓语动词
与现在事实相反 动词过去式 SHOULD+动词原形
WOULD+动词原形
与过去事实相反 HAD+过去分词 SHOULD HAVE +过去分词
WOULD HAVE +过去分词
与将来事实可能 动词过去式 SHOULD+动词原形
相反 SHOULD+动词原形 WOULD+动词原形
WERE TO+动词原形
注、：1在主句中SHOULD 用于第一人称，WOULD 用于任何人称。
2主句中可用COULD，MIGHT代替SHOULD WOULD。
3条件从句中一律用WERE，在口语或非正式语句中用WAS。但“IF I WERE YOU…… ”是固定说法