mutually perpendicular lines

This thesis s research object is four adverbs of "huxiang", "xianghu", "hu" and "xiang" which expresses mode in the modal adverb, and they are called by a joint name of "huxiang" category adverb.

本文的研究对象为情态副词中表方式的“互相”、“相互”、“互”、“相”四个副词,我们统称为“互相”类副词。