asto、asfor与aswith的区别Grammar
as to
1. 提及某人或事，不涉及讲话人的态度。
As to your ability to overfulfil the target，I never had the slightest doubt．
2. 引出做事的依据：“按照”、“根据”
The shoes are correctly placed on the shelf as to size and colour．
3. 用以重提旧事，as to引出的内容都是前文曾经提到过的或者谈话对方都有所了解的，表示“说到”之义。
As to doing that，I haven't decided yet．
含有绿字的古诗4. 用于提出问题：as to必须位于句中，前面出现的大都是表达某种心理活动的动词，形容词或名词，其后引接出wh-clau或who-to-v结构，表示“在……的问题上”、“就……问题来讲”。
属鼠和属兔
我是一张纸
There is some doubt as to whether the proposal is practicable．
5. This gave me a clue as to the source of the problem.这件事给我提供了找出问题根源的线索。
as for
1. 用以转换话题, 与前文形成对照，译作“至于”。
音响没有声音
You have a bed；as for him，he'll have to sleep on the floor．
如何玩母猪2. 用以表现态度,带有贬义。译作汉语的“至于……嘛”。
As for his songs，I suppo you've read the sarcastic reviews !广元旅游
3. as for 通常总是放在句首a股
As for that，we shall e later．至于那件事，往后我们便见分晓了。
4. 对于突然想到的事情或临时提起的问题，以使用as for为宜，并可引导动名词短语。
圆明园的历史简介
Much pasture land is under water；and as for the grain, most of it has been ruined．
许多牧场被水淹了；至于粮食，大部分也毁了。（粮食是临时想到的，用as for来引导比较合适。）
as with
正如，与……一样
As with Vegas, what you do in Second Life stays in Second life.
和威维加斯一样，你在第二人生中做的事情保留在第二人生中。
As with the food, all people regardless of weight need physical activity to be healthy.
正如食物，所有那些不顾及体重的人都需要体育运动以获得健康。
