As+形容词或副词+aspossibe,意思是"尽可能……的"。例句：We have to run as fast as possible.我们得尽可能快的跑。（fast属于副词）

as习惯用法

　　1. as soon as

　　意思是"一......就......",引导一个时间状语从句。如：I'll call you as soon as I finish my homework. 我一完成我的作业,就给你打电话。

　　2. as long as

　　意思是"长达......之久；只要......"。如：She has searched the information about dinosaurs on the Internet as long as three hours. 她在因特网上搜索有关恐龙的信息已经长达三个小时。

　　3. as much as

　　意思是"高达......；与......一样多"。是用来表达极其多的语气。如：Some of the stones weigh as much as fifteen tons.有些石头重达15吨。

　　as...as用法：

　　as...as意为"和……一样"，表示同级的比较。使用时要注意第一个as为副词，第二个as为连词。其基本结构为：as+adj./adv.+as。