as much as one can do

do 可以用任何实意动词来代替。给你举些例子
as much as you can try, as much as you can get, as much as you can eat,as much as you can learn.

The child can eat bread as much as his father can do.

How do you do?

do 是助动词，可以替换为实意动词，即有自己意思的动词~，当后面需要重复使用这个动词时就可以用助动词do ，does，注意时态啊