例句:Whether she will come or not is still a question.
这里有一个引导词whether,所以Whether she will come or not这部分是从句。
而这部分在句子里是主语,句子的谓语是is,表语是still a question
whether位于句首引导主语从句。例句:The jury is out on whether or not this is true.这是否属实尚无定论。It remains to be seen whether his project will fly.他的计划能否成功尚需拭目以待