each other
(used only as the object of a v or prep 僅用作動詞或介詞的賓語) the other one, reciprocally 互相; 彼此
Paul and Linda helped each other, ie Paul helped Linda and Linda helped Paul. 保羅和琳達互相幫助.
We write to each other regularly. 我們彼此經常通信. Cf 參看 one another (one3).