英语中的句法结构歧义

                                这是帆船？是桥洞？还是牙齿？

       英语中的句法结构歧义—三谈歧义是自然语言中的普遍现象

                                  冯志伟

英语中的歧义（ambiguity）不仅存在于词义（sense）和词类（part of speech）中，而且也存在于句法结构中。

如果一个语法可以把一个以上的剖析指派给同一个句子，那么，我们就说，这个句子具有结构歧义（structure ambiguity）。

在上面的图中，为我们似乎看到了一排大帆船，又似乎看到了一连串的桥洞，又似乎看到了一排牙齿，它们的结构各异，究竟是什么，使我们感到迷惘，这就是结构歧义。

英语中主要有三种结构歧义：附着歧义（attachment ambiguity），并列歧义（coordination ambiguity）和名词短语括号歧义（noun-phrase bracketing ambiguity）。此外，还有其他类型的结构歧义，我们在这里也做简单的介绍。

   ——附着歧义（Attachment ambiguity）

a)  PP附着歧义（PP attachment ambiguity）

介词短语（Preposition Phrase，简称PP，可能做句子中动词短语的修饰语，又可能做名词短语的修饰语，造成PP附着歧义。例如，如果我们有英语句子“They made a report about the ship”和“On the ship, they made a report”，这两个句子是没有歧义的，但是，如果我们把它们改写成句子“They made a report on the ship”，“on the ship”这个PP可以修饰动词made，也可以修饰名词report，就产生了PP附着歧义。我们可以把这种 PP附着歧义写为如下形式：

1) They made a report about the ship.

   On the ship, they made a report.

   ->They made a report on the ship.

另外的例子还有：

2) They made a decision concerning the boat.

   On the boat, they made a decision.

   -> They made a decision on the boat.

3)      He drove the car which was near the post office.

Near the post office, he drove the car.

-> He drove the car near the post office.

4) They are walking around the lake which is situated in the park.

   In the park, they are walking around the lake.

   -> They are walking around the lake in the park.

5) He shot at the man who was with a gun.

   With a gun, he shot at the man.

   -> He shot at the man with a gun.

6) The policeman arrested the thief who was in the room.

   In the room, the policeman arrested the thief.

   -> The policeman arrested the thief in the room.

Church and Patil (1982)证明了，在带多个介词短语PP的名词短语中，名词短语剖析结果的歧义的数量随着介词短语PP的数量的增加而增加，其增加速率与算术表达式的插入数（number of parenthesization）相同。这个插入问题是按照Catalan数（Catalan number）以指数增长的。

b)      动名词附着歧义（Gerundive attachment ambiguity）

英语句子中的动名词可能修饰中心动词，作为动词的状语，也可能作为动词宾语从句中的谓语，从而引起结构歧义。

例如。在句子“We saw the Eiffel tower flying to Paris”中，动名词短语“flying to Paris”可能修饰动词“saw”，作为“saw”的状语，句子的意思是“我们飞到巴黎时看到了埃菲尔铁塔”；但是，“flying to Paris”也可能作为动词“saw”的从句“the Eiffel tower flying to Paris”中的谓语，句子的意思是“我们看到埃菲尔铁塔正向巴黎飞来”。当然，后面这种情况只在神话世界或者童话世界中才可能发生。

另外的例子还有：

2) I saw that a boy was swimming in the river.

I saw a boy who was swimming in the river.

I saw a boy while I was swimming in the river.

-> I saw a boy swimming in the river.

3) I noticed that the man was smoking in the corridor.

   I noticed the man who was smoking in the corridor.

   I noticed the man while smoking in the corridor.

   -> I noticed the man smoking in the corridor.

c) 局部歧义（local ambiguity）

如果整个的句子是没有歧义的，但是这个句子中的某些部分在剖析过程中可能是有歧义的，这时，就会发生局部歧义。

例如，句子 “book that flight”是没有歧义的，但是，在剖析过程中，当剖析程序扫描到单词 “book”的时候，可能辨不清这个book是动词还是名词，在这种情况下，就应该采用回溯（backtracking）或者并行分析（parallelism）的办法，同时考虑到两种可能的剖析。“book”实际上是一个兼类词，如果我们在形态分析的时候，就进行了兼类词“book”的歧义消解，就可以大大减少这样的局部歧义问题。

——并列歧义（Coordination ambiguity）

并列歧义是由and引起的歧义。

下面是并列歧义的例子，箭头后面的句子是有并列歧义的：

1) She looks care of old men and old women.

   She looks care of women and old men.

   -> She looks care of old men and women.

2) Mr. John is a scientist of great fame and a professor of great fame.

   Mr. John is a professor of great fame and a scientist.

   -> Mr. John is a scientist and a professor of great fame.

3) Someone tells me he’s cheating, and I can’t do anything about it.

   Someone tells me that he’s cheating and that I can’t do anything about it.

   -> Someone tells me he’s cheating and I can’t do anything about it.

4) John will go, or Dick and Tom will go.

   John or Dick will go, and Tom will go.

   -> John or Dick and Tom will go.

    ——名词短语括号歧义（Noun-phrase bracketing ambiguity）

在名词短语“ADJ + N1 + N2”中，形容词ADJ可能修饰N1+N2，也可能只修饰N1，从而形成歧义。第一种情况可用括号表示为NP(ADJ(NP(N1 N2)))。第二种情况可用括号表示为NP(NP(ADJ N1)N2)。这种歧义可用括号式说明：

             NP(ADJ(NP(N1 N2)))     NP(NP(ADJ N1)N2):

下面是名词短语括号歧义的例子，箭头后面的句子是有名词短语括号歧义的：

1)      The salesman who sells old cars is busy.

The old salesman who sells cars is busy.

-> The old car salesman is busy.

2) He is a Department Head, who is from England.

   He is Head of the English Department.

   -> He is an English Department Head.

以上是英语中三种主要的歧义结构，此外，英语中还有很多歧义结构，下面，我们做进一步说明。

    ——歧义结构‘Somebody is + V-ing + N’

V-ing可能修饰N，形成NP，V-ing也可能与前面的is结合，形成VP，从而产生了歧义。

例如：

1) They are receiving women as guest.

   They are amusing women.

-> They are entertaining women.（entertaining有“接待”和“快乐”等不同含义）

2) They are flying the planes.

   They are the flying planes.

   -> They are flying planes.

3) They are roses which are growing.

   They are cultivating roses.

-> They are growing roses.

4) They are having apples.

They are apples for eating.

  -> They are eating apples.

    ——歧义结构 ‘somebody has + V-ed  + N’

V-ed可能修饰N，形成NP，V-ed也可能与前面的has结合，形成VP，从而产生歧义。

例如，

1) He has already discarded boots.

   He has a pair of discarded boots.

   -> He has discarded boots.

2) They have used cars as a transportation tool.

    They have a few used cars.

   -> They have used cars.

——动词不定式造成的歧义

动词不定式可能做它前面的名词的修饰语，也可能做中心动词的状语，从而产生歧义。

例如，

1) He wants an assistant who can finish the experiment.

   To finish the experiment, he wants an assistant.

   -> He wants an assistant to finish the experiment.

2) The students will discuss their plan about a dance party that they are to hold.

   In order to hold a dance party, the students will discuss their plan.

   -> The students will discuss their plan to hold a dance party.

    ——歧义结构‘Something is not to do’

not可能与它前面的is相结合，形成否定形式is not，not也可能与它后面的to do结合，形成not to do，从而产生歧义。

例如，

His object isn’t to eat（他的目的不是吃）.

   Not to eat is his object.（他的目的是不吃）

-> His object is not to eat.

    ——歧义结构‘something is ready to do’

这种结构中的is ready可能表示主动态，也可能表示被动态，从而形成歧义。

例如，

1) The chicken is ready to eat some food.

   The chicken is ready to be eaten.

   -> The chicken is ready to eat.

2) The horse itself is ready to ride on the track (on the way).

   The horse is ready for someone to ride.

   -> The horse is ready to ride.

    ——‘V-ing’引起的歧义

‘V-ing’可能具有主动和被动两种含义，从而引起歧义。

例如，

1) John likes to question scientist.

   John likes scientist who often asks questions.

  -> John likes questioning scientist.

2) The way of the hunter shot was terrible.

   That the hunter was shot was terrible.

-> The shooting of the hunter was terrible.

    ——双宾语引起的歧义

her可能做双宾语中的间接宾语的修饰语，也可能单独做间接宾语，从而引起歧义。

例如，

1) Mary gave picture to her baby.

   Mary gave baby picture to her.

   -> Mary gave her baby picture.

2) Mary taught manners to her child.

   Mary taught child manners to her.

   -> Mary taught her child manners.

    ——歧义结构 ‘V + her + 动名兼类词’

当动名兼类词解释为名词时，her是这个名词的修饰语，当动名兼类词解释为动词时，her是这个动词的宾语，从而形成歧义。

例如，

1) I heard that she cried to help.

   I heard her loud cry for help.

   -> I heard her cry for help.

2) I saw the wonder she had done.

   I saw her feel greatly surprised.

  -> I saw her wonder. （wonder有“奇迹”和“惊奇”等不同含义） 

3) I saw her remain awake.

   I saw the watch belonged to her.

   -> I saw her watch.（watch有“观察”和“手表”等不同含义）

4) I saw her lower her head.

   I saw the duck which belonged to her.

   -> I saw her duck.（duck有“低头”和“鸭子”等不同含义）

    ——歧义结构 ‘V + somebody + V-ed’

V-ed可能做somebody的修饰语，也可能做从句中的谓语，从而产生歧义。

例如，

She found that a boy was hidden behind the door.

   She found a boy who was hidden behind the door.

   -> She found a boy hidden behind the door.

——歧义结构 ‘V + somebody + who clause’

‘who clause’可能做somebody的修饰语，也可能做动词V的宾语从句，从而产生歧义。

例如，

1)      I asked the professor, who would give the lecture.

I ask the professor. This professor would give the lecture.

    -> I asked the professor who would give the lecture.

2)      John asked the lady, who was sitting on the stairs.

John asked the lady. She was sitting on the stairs.

-> John asked the lady who was sitting on the stairs.

    ——歧义结构‘V + somebody + when clause’

‘when clause’可能做动词V的时间状语，也可能做动词V的宾语从句，从而产生歧义。

例如，

Tell me at what time you are free.

   When you are free, tell me.

   -> Tell me when you are free.

    ——歧义结构‘V + somebody + if clause’

‘if clause’可能做动词V的条件从句，也可能做动词V的宾语从句，从而产生歧义。

例如，

1) Tell me whether you have time or not.

   If you have time, tell me.

   -> Tell me if you have time.

    ——歧义结构 ‘V + if clause’

这种歧义结构与前面的歧义结构类似。‘if clause’可能做动词V的条件从句，也可能做动词V的宾语从句，从而产生歧义。

例如，

Let me know whether you’re coming or not.

   If you’re coming, let me know.

   -> Let me know if you’re coming.

    ——修饰语的歧义

由修饰语产生的歧义有各种不同的情况，从下面的例句中，大家不难看出它们的差别来。

1) It is a pretty skirt for a little girl

   It is a fairly (=pretty) little skirt for a girl.

   It is an attractive (=pretty) little skirt for a girl

   It is a skirt for a fairly little girl.

   It is a skirt for an attractive little girl.

   -> It is a pretty little girl’s skirt.

2) Do you happen to know the gentleman next to the lady who is reading a book?

   Do you happen to know the gentleman who is reading a book, next to the lady?

   -> Do you happen to know the gentleman next to the lady reading a book.

3) I recommended John to Tom. The former was approachable.

   I recommended John to Tom. The latter was approachable.

   -> I recommended John to Tom who was approachable.

4) I like the books on the shelves. I bought the shelves yesterday.

   I like the books on the shelves. I bought the books yesterday.

   -> I like the books on the shelves I bought yesterday.

5) There is a theatre located near the business district. The theatre is crowded every night.

   There is a theatre near the business district. The business district is crowded every night.

   -> There is a theatre near the business district which is crowded every night.

6) The secretary granted my request namely that I might see the president.

   The secretary granted my request so that I might see the president.

   -> The secretary granted my request that I might see the president.

    ——状语的歧义

由状语产生的歧义有各种不同的情况，从下面的例句中，读者不难看出它们的差别来。

1) When you are free, tell him.

   Tell him at what time you are free.

   -> Tell him when you are free.

2) If you have time, tell me.

   Tell me whether you have time or not.

   -> Tell me if you have time.

3) She knew that, before I met you, you had begun to study NLP.

   Before I met you, she knew that you had begun to study NLP.

   -> She knew that you had begun to study NLP before I met you.

由此可见，歧义不仅存在于词义中，不仅存在于词类中，而且也存在于句法结构中，歧义是自然语言重的普遍现象。我们必须注意歧义问题的研究。