Frendiship is to a person ____ water is to fish.为什么这题不填as?友谊

Frendiship is to a person ____ water is to fish.为什么这题不填as?友谊 as air is to man,so is water to fish. as water is to fish,so air is to man As water is to fish,so is air to man air is to us___ water is to fish可以填as吗?为什么? As water is the fish ,so you is to me As air to man ,so is water to fish 中文意思,什么句式? ari water is to fish,so air is to man. ______ air is to man,so is water to fish. imagination is to artists what water is to fish. what environment is to man,what is water to fish. "Water is to fish （ ）air is to man"