许多同学们（包括部分老师）都错误地认为，同位语从句不重要，一般不会考。但不一定。请看几道考题：
—It’s thirty years since we last met.—But I still remember the story, believe it or not, _______ we got lost on a rainy night. (四川卷)A. which B. that C. what D. when答案为B。that在此引导同位语从句，修饰名词the story。此题的难点是，其中插入了believe it or not，使问题变得复杂了。
Nobody believed his reason for being absent from class _______ he had to meet his uncle at the airport. (重庆卷)A. why B. that C. where D. because答案为B。that在此引导同位语从句，修饰名词his reason。此题的难点是，his reason后带有用作定语的介词短语for being absent from class，如果撇开这个介词短语，问题就变得简单了。
Doris’ success lies in the fact _______ she is co-operative and eager to learn from others. (上海卷)A. which B. that C. when D. why答案为B。that在此引导同位语从句，修饰名词the fact。END
两者的共同点是：均可引导让步状语从句，且可换用。如：Whatever (=No matter what) you say, I believe you. 无论你说什么，我都相信你。
两点的不同点是：引导名词性从句时只能用whatever，不能用no matter what。如：她要他做什么，他就做什么。误：He does no matter what she asks him to do.正：He does whatever she asks him to do.注：whoever与no matter who的区别以及whichever与no matter which的区别也符合以上原则。Whoever (=No matter who) telephones, tell them I’m out. 不管是谁打电话，都说我出去了。Whichever (=No matter which) day you come, I’ll be pleased to see you. 无论你哪天来，我都欢迎。END