很早的時(shí)候,like是形容詞,表示相象、相同、類似等意；as是連接詞.
Samy and Sammy are very like.Samy和Sammy長得很像.
Paul behaved as a child（does）．保羅的舉止像個(gè)小孩.（句子有省略）
后來,like作為介詞使用,表示像…一樣；as也可以作為介詞使用了.
Paul behaved like a child．保羅的舉止像個(gè)小孩.（句子沒有省略）
再比較：
Let me speak to you as a father．讓我以父親的地位對(duì)你說說.（=I am your father and I am speaking to you in that character）
Let me speak to you like a father．讓我像你父親那樣對(duì)你說說.（= I am not your father but I am speaking to you in the way your father might）
再后來,有些語法學(xué)家把以往like不允許作連詞使用的規(guī)則也改了,用來代替引導(dǎo)方式狀語從句的as.
I can't sing like I used to do．我不能像過去那樣地唱了.（指唱的音色）
He writes just like his brother did when he was young．他寫字的手法和他兄弟年輕時(shí)寫的差不離.（指書法的風(fēng)格和字型）
即使如此,like和as有時(shí)還是有些區(qū)別的.試比較：
The prisoner was hanged like a murderer．這個(gè)囚徒像殺人犯那樣被處以絞刑（=…as if he were a murderer）.
The prisoner was hanged as a murderer．這個(gè)犯人作為殺人犯被處以絞刑.（這個(gè)犯人就是殺人犯）