as to sth.
1. concerning “关于……方面”、“有关……的事”,多用于句中,但也可置于句首,以示强调。
As to the flood, I have heard nothing. 至于那次水灾,我没听到什么。
2.(较正式)开始谈论和刚才话题有关的新内容时,多用于句中,后接wh-从句或带疑问词的不定式,表示“在……问题上”、“就……问题来讲”。
He is very uncertain as to whether it's the right job for him. 关于他究竟是否适合做这项工作,他实在拿不准。
Nobody could decide (as to) what to do. 谁也不能决定该做些什么。
3. 引出做事的根据,意思是“按照”、“根据”。
They sorted the eggs as to size and color. 他们按照大小和颜色将鸡蛋进行分类。
as for sth./ sb.
在有前文的情况下,多置于下文之首,用来引出另外的一方或新的谈话内容(着重话题的转移),但与前文内容也有一定的联系,起到补充前文而又突出后文的作用,使之与前文形成对照。
You can have a bed; as for him, he’ll have to sleep on the floor. 有一张床给你,至于他,就只能睡在地板上了。
Much pasture land is under water; as for the grain, most of that has been ruined. 大部分的牧场都进了水,至于谷物,则大部分都被冲毁了。