1.用于指距离,表示“直到……为止”之意时,as far as既可用于肯定句,也可用于否定句,但so far as只能用于否定句中.例如：We went as far as Lion Rock Tunnel.我们一直走到狮子山隧道公路那儿.
They did not go as far as the others.他们没有像其他的人走得那么远.
（此句的as far as可以改作so far as）
（二）在表示“直到……程度”之意的借喻说法中,as far as和so far as都可使用,但前者不及后者用得普遍.例：she went so far as （or as far as） to call him a coward.她甚至骂他是儒夫.
（三）在表示“就……而论”之意时,as far as和so far as可互换使用.例：As （or So） far as I koow,she will be away from Macao for two months.
据我所知,她将要离开澳门两个月.
As （or So） far as my knowledge goes,there is no such word in English.
据我所知,英语里没有这样一个字.
(四）在表示“只要”、“尽……所能”之意时,应用as far as,不用so far as.例：I'll do my utmost to help you as far as I can.
只要可能,我一定竭尽全力来帮你.Eric Partridge在他编著的Usage and Abusage一书中写道（第44页）,在用作比喻意义的叙述句里,so far as比as far as用得普遍,他举了这样一个例子：so far as I can see,your idea is admirable.无事.
