A subordinate clause can not stand alone as a sentence - that is a sentence fragment.

附属从句是不能单独作为一个句子的，附属从句是属于残缺句。

But-unless there's a very good reason for including it-one long sentence among several fragment subheadings will stand out, and not in a good way.

除非你有特殊需要，一个完整的句子标题和几个片语副标题的组合并不是最好的主意。