for和of引導(dǎo)的不定式結(jié)構(gòu)的區(qū)別
不定式是一種非謂語動(dòng)詞,不能單獨(dú)作謂語,因此沒有語法上的主語.但由于不定式表示的是動(dòng)作,在意義上可以有它的主體.我們稱之為邏輯主語.
提起不定式邏輯主語,人們首先想到的會(huì)是“for+名詞（賓格代詞）+不定式”的復(fù)合結(jié)構(gòu).如：It is important for us to study English well．然而,有時(shí)不定式的邏輯主語須要用“of+名詞（代詞賓格）”才行.例如：It iskind of you to help me．而不能說：It is kind for you to help me．在選擇介詞“for”還是“of”時(shí),人們往往總是憑感覺而定.有時(shí)受習(xí)慣影響,多選介詞“for”.于是常出現(xiàn)這樣的錯(cuò)誤：It was careless for him to lose his way．It is cruel for you to do so．由于眾多語法書對(duì)這種結(jié)構(gòu)中使用“for”與“of”的區(qū)別介紹甚少,一些人對(duì)其概念認(rèn)識(shí)尚不完全清楚,筆者認(rèn)為有必要就這一問題作些探討與介紹.
一、在句中的語法作用不同
a．不定式for結(jié)構(gòu)在句中可以作主、賓、表、定、狀、同位語：
1．It is easy for Tom to do this work．（主語）湯姆做此工作是容易的.
2．I'd like for him to come here．（賓語）我喜歡他來這里.
3．His idea is for us to travel in two different groups．（表語）他的想法是：我們分成兩組旅行.
4．Have you heard about the plan for you to go abroad．（定語）你聽到讓你出國(guó)的計(jì)劃嗎?
5．The word is too difficult for him to pronounce well．（狀語）這單詞太難,他念不準(zhǔn).
6．In the most schools,it is the custom for the headmaster to declare the newterm start．在大部分學(xué)校,校長(zhǎng)宣布新學(xué)期開始是一個(gè)習(xí)慣.
b．不定式of結(jié)構(gòu)只能在句中作主語.
1．It was careless of him to leave his umbrella in the train．他把傘丟在火車上真是太粗心了.
2．It is awfully good of you to come to see me off at the station．謝謝你來車站送我.
二、邏輯主語的名詞有所不同
a．不定式for結(jié)構(gòu)中的名詞可以是人,也可以是無生命的事物：
1．It is very important for us to study English well．我們學(xué)好英語是非常重要的.
2．It is essential for the classroom to have plenty of light．教室光線充足是必要的.
有時(shí)還可以是引導(dǎo)詞“there”：
3．It is a pity for there to be any disagreement in the family．家庭不和實(shí)在是很遺憾.
4．In such case it is impossible for there to be an escape of air from the con-tainer．在這種情況下,不存在空氣從容器溢出的可能性.
b．不定式of結(jié)構(gòu)中的名詞只能是人：
It is foolish of you to lend the money．你借錢給人真是太蠢了.
三、表語形容詞的語義不同
表語形容詞的語義不同是區(qū)別for結(jié)構(gòu)和of結(jié)構(gòu)的最重要標(biāo)志.
a．在“It is（was）+adj．+for sb+to do sth”的句式中,作表語的形容詞大多是表事物性質(zhì)的靜態(tài)形容詞（stative adjective）,如：essential,easy,difficult,important,neccessary,（im）possible,hard等等,這類形容詞與for后面的名詞（代詞）關(guān)系不密切,無意義上的主表關(guān)系.例如：
It is neccessary for us to practise speaking English every day．
句中不定式邏輯主語“us”與表語形容詞“neccessary”無主表關(guān)系,我們不能說：We are neccessary to practise speaking English every day．因?yàn)椤叭恕保╳e）不能與表“事物性質(zhì)的形容詞”（neccessary）連用在一起.此句的重點(diǎn),是強(qiáng)調(diào)“每天練習(xí)說英語”這件事.同樣：It was very difficult for Tom to answer this question．不能說成：Tom was very difficult to answer this question．而可以說：For Tom to answer this question was very difficult．
b．在“It is（was）+ adj．+ of sb…”的句式中,作表語的形容詞大多是表示人物特征的形容詞.如：bold,absurd,brave,careless,careful,clever,considerate,cruel,foolish,good,honest,（un）kind noble,impudent,polite,right,rude,sweet,nutured,silly,stupid,selfish,thoughtful,ungrateful,wicked,unmanly,（un）wise,wrong等等.這些表示人物特征的形容詞與of后的名詞關(guān)系十分密切,有意義上的主表關(guān)系.如：
1．It is selfish of you to do so．
“you”與“selfish”關(guān)系密切.“you”既是不定式“to do so”的邏輯主語,又是形容詞“selfish”的邏輯主語.此句重點(diǎn)強(qiáng)調(diào)的是“人”,（你這人太自私了）故可以說成：You are selfish to do so．又如：
2．It is kind of you（= You are kind）to send me a nice present．謝謝你送我這么好的禮物.
3．It was stupid of her（=she was stupid）to make such a mistake．出這樣的錯(cuò)她真是太蠢了.
另外,在這個(gè)句式中,“it”可以根據(jù)情況改為“that”、“this”,如：
4．That is very kind of you．謝謝你.
5．This is very good of you to repair the TV set for me．謝謝你幫我修電視機(jī).
較長(zhǎng)的句子,還可以加逗號(hào),在of sb與to do sth中間停頓一下：
6．That was smart of you,to hush up the affair before you heard about it．聽到此事之前能保持緘默,你是很聰明的.
四、句子的語氣有所不同
A．在較多的場(chǎng)合中,不定式for結(jié)構(gòu)的句式語氣帶有情態(tài)意義.for sb todo sth．的復(fù)合結(jié)構(gòu),相當(dāng)于一個(gè)有情態(tài)動(dòng)詞的主語從句.例如：
1．It is neccessary for us to get the preparations done．=（… that weshould get the preparations done．）我們有必要（應(yīng)該）把準(zhǔn)備工作做好.
2．It is hard for which one to be given the reward to．=（… which oneshould be given the reward to．）難就難在應(yīng)該給哪個(gè)人授獎(jiǎng).
3．In the old society,it was rare for a poor man's son to go to college．（=… that a poor man's son could go to college．）舊社會(huì),窮人的孩子能上大學(xué)是很少見的.
B．不定式of結(jié)構(gòu)的句式,在語氣上往往對(duì)前面表人物特征的表語形容詞有著某種感嘆意味.It is／was adj．of sb相當(dāng)于How adj of sb it is／was．故在翻譯時(shí),多加上“太……”“真是……”“實(shí)在是……”等字眼,如前面提到的諸例句：
1．It was careless of him to leave his umbrella in the train．（= How carelessof him（it was）to leave his umbrella in the train．）他太粗心了,竟會(huì)把傘忘在車上.
2．That was stupid of you to make such a mistake．（= How stupid of you tomake such a mistake．）你竟然會(huì)犯這樣的錯(cuò)誤,真是太蠢了.
有時(shí),為了加強(qiáng)感嘆的程度還可以在表語形容詞前加上修飾詞：
3．That is really kind of you．
4．It is awfully good of him to come to see us off at the station．
五、由于某些形容詞（如：good,right,foolish,wrong,silly…）在語義上具有兩重性,既可以表人物的特征,又可以說明事物的性質(zhì),因此它們可以使用在for結(jié)構(gòu)中,也可以使用在of結(jié)構(gòu)中,但兩種結(jié)構(gòu)在意義上有所區(qū)別.試比較：
1．It is good for Xiao Wang to travel abroad．（= It's good to travel abroad for-Xiao Wang）中心意思是說“旅行是件好事”,重點(diǎn)在“to travel abroad”不定式所表示的動(dòng)作.“for Xiao Wang”只表示一種范圍.（對(duì)于小王來說）
2．It is good of Xiao Wang to lend me the money．
“of”表示一種所屬關(guān)系,“good”是“Xiao Wang”的所屬特征.中心意思是說“小王心眼真好”,重點(diǎn)在“Xiao Wang”這個(gè)人上.又如：
3．It is foolish of you to buy that book．（= You are foolish to buy that book．）你這人真傻,竟買了那本書.（強(qiáng)調(diào)“你傻”）
4．It is foolish for you to buy that book．（=For you to buy that book is fool-ish（= It is foolish to buy that book for you．）你買那本書是愚蠢的.（強(qiáng)調(diào)“買那本書”這件事很傻）
參考資料：http://218.24.233.167:8000/Resource/GZ/GZYY/YYXKLW/JXFF/XYYGLSC/421f0065zw_0137.htm to 表示目的 方向
for 譯 為. 后接名詞
of 一般譯成 .的 與其后的名詞 相當(dāng)與形容詞
例One of the legs of the table was broken.桌子的一條腿斷了