as for (至于,就……方面說)和 as to (至于；關(guān)于)這兩個復(fù)合介詞在含義上相當接近,但在用法上差別很多.下面談它們的這些差別.
1．a(chǎn)s for
1)用以轉(zhuǎn)換話題：在有前文的情況下as for總是出現(xiàn)在下文的句首,用來引出另外一方或者新的談話內(nèi)容,但與前文內(nèi)容也有一定的聯(lián)系,起到補充前文又突出后文的作用,使之與前文形成對照,譯作“至于”.例如：
①You van have a bed；as for him,he'll have to sleep on the floor．
②Much pasture land is underwater；and as for the grain,most of that has been ruined．
2)用以表現(xiàn)態(tài)度：as for還可以用來表示講話人對某人或某物持有“輕蔑”或“冷淡”的態(tài)度,甚至有憎惡之感,講話時要重讀引出的詞語并在其后稍作停頓,以示強調(diào),口氣上帶有嘲諷意味,譯作漢語的“至于……嘛”.例如：
①As for you,I never want to see you here in my home again．
②As for his songs,I suppose you've read the sarcastic reviews !
2．a(chǎn)s to
1)表示涉及某點：as to常放于句中,表示“關(guān)于……方面”、“有關(guān)……之事”,但為了突出要提及的人或事之時,也可將as to置于句首,以示強調(diào).但只涉及內(nèi)容,而不涉及講話人的態(tài)度.例如：
①His wife,an old teacher,has n0 complaint as to salary．
②As to your ability to overfulfil the target,I never had the slightest doubt．
2)用以重提舊事：as to引出的內(nèi)容都是前文曾經(jīng)提到過的或者談話對方都有所了解的,表示“說到”之義.,例如：
①As to doing that,I haven't decided yet．
②As to the question you raised in your last letter,I think that it is
unanswerable．
3)用于提出問題：as to必須位于句中,前面出現(xiàn)的大都是表達某種心理活動的動詞,形容詞或名詞,其后引接出wh-clause或who-to-v結(jié)構(gòu),表示“在……的問題上”、“就……問題來講”,所引出的問題都有很強的針對性.但有人認為這里的罄to顯得多余,去之亦通.所以,有時也不必譯出.例如：
①There is some doubt as to whether the proposal is practicable．
②I enquired of the clerk as to which documents were needed．
4．引出做事的依據(jù)：as to還有“按照”、“根據(jù)”的含義,而as for則無此義.例如：
①The shoes are correctly placed on the shelf as to size and colour．
②The items on the agenda are listed as to order of importance．
綜上所述,as for 和 as to在確切含義的表達和具體用法上都是有很大差別的,不能將二者混為一談.