as .as you can 尽你所能as.as possible 尽可能
第一个结构中第一个as是副词,后面可以跟副词或者形容词,第二个as是连词,后面跟了个句子as you can.例如,You should come here as soon as you can.第二个结构中两个as都是副词.例如,Come to see me as soon as possible.
PS.as soon as possible经常被外国人简略成ASAP