互相（Adv.） "each other; mutually"

    互相 means either "A to B" or "B to A" is doing the same or has some relationships.
                 Subj.+互相+VP
Examples:
1. 朋友应该互相帮忙。
Friend should help each other.
2. 我们生意上互相照顾。
We take care of each other's business.

Substitutive drills: