1、中文：我要是你，我不会那么做。
(误)I shouldn't do that if I was you.
(正)I shouldn't do that if I were you.(表示与现在事实相反的虚拟语气不能用was，只能用were.)
2、中文：要是我父亲现在在这里，他会告诉我该做什么。
(误)If my father were here now，he will tell me what to do.
(正)If my father were here now，he would tell me what to do.(表示与现在事实相反的虚拟语气中，主句的助动词只能用would，might等过去时。)
3、中文：要是我知道她的电话号码，我就会给她打电话了。
(误)If I knew her telephone number，I would have called her.
(正)If I had known her telephone number，I would have called her.(表示与过去事实相反的虚拟语气中，条件从句的动词要用过去完成时。)
4、中文：要是昨天没下雨她也许会来。
(误)If it had not rained yesterday，he might come.
(正)If it had not rained yesterday，he might have come.(表示与过去事实相反的虚拟语气中，主句的动词要用助动词的过去时might，could等+HAVE+过去分词。)
5、中文：我不认为我会失败，但要是我失败了，我会再努力。
(误)I don't think that I shall fail. But if I failed，I would try again.
(正)I don't think that I shall fail. But if I should fail，I would try again.(表示与将来事实相反的虚拟语气中，条件从句的动词用should加原形动词。)
6、中文：他要是带了钱就会买它。
(误)Did he bring some money with him，he would have bought it.
(正)Had he brought some money with him，he would have bought it.(表示与过去事实相反的虚拟语气中，条件从句的动词要用过去完成时，若省略if，则用倒装形式。)
