【正文】 one hand, it means “I saw the girl when I was at the bookshop”。 on the other hand, it means “I saw the girl who was at the bookshop.” 2) I found John an experienced doctor.This sentence also has ambiguity, and the transitive verb “found” was followed by two nouns, “John “and “an experienced doctor”. First, it can refer “I discovered that John was an experienced doctor”. Second, it also means “I succeed in finding an experienced doctor for John”. Pragmatic Ambiguity Pragmatic ambiguity is also a very mon phenomenon in the research of ambiguity. People always put the ambiguity into the range of pragmatics and go on a dynamic research. The speakers will use the words not surely and indirectly on the specific context, which may let the listeners have more extra imagination. Consequently, pragmatic ambiguity can not be understood so directly. Sometimes people only can understand the real intention when they use pragmatic knowledge, or turn to some pragmatic derivation. This paper will talk about two causes for pragmatic ambiguity, and they are dexis and implicature. Dexis and Pragmatic ambiguityDexis is a mon phenomenon in the pragmatic study, and it exits in every language. Dexis is the word or phrase indicated in the context. They are used to point out the indicating message in the conversation, and to state space, time, and social environment. The dexis phases may be the personal pronoun, indicated pronoun, some verbs, and some adverbs and so on.For example: 1) Jane told her mother she had acted foolishly.In this sentence, the dexis “she” not only can indicate the object “Jane”, but also can indicate “her mother”, and so obviously, there is ambiguity in this sentence. On one side, it means “Jane acted foolishly”, but on the other side, it means “Jane’s mother acted foolishly.” 2) Jane greeted me by my first name and handed me a letter, but this didn’t surprise me. In this sentence, the dexis word “this” not only can indicate “Jane greeted me by my first name”, but also can indicate “Jane handed me a letter”. For this reason, the sentence has ambiguity surely. Implicature and Pragmatic ambiguityAs we all know, a sentence sometimes can’t reflect the speaker’s real meaning. In another way, we say this sentence has its implicature in the munication, and the implicature is a very important subject in the pragmatics. Implicature means people research the true meaning of the sentence not from the inner system of the language, but from the language context to understand its denotation. In another word, speakers may endow the sentence with action purpose. And as Grice said, if we want the social activity to go on successfully, we should ply with four cooperation principles, quantity maxim, quality maxim, relation maxim and manner maxim. But if we infringe one of these principles, it will produce the implicature which may cause ambiguity.For example: 1) A: whoa! Has your boss gone crazy? B: Let’s go and get some coffee.In this dialogue, B violates the relation maxim. B may think what A said is not suitable, and he is afraid that the walls have ears。 maybe his boss is in next door. So he changed the topic of conversation and said the unrelated thing. 2) A: Let’s get the kids something. B: Okay, but I vote ICECREAM. This dialogue infringes the manner maxim, and what B speaks beating around the bush. B haven’t said ice cream directly, but said the letters one by one. His purpose is to make the kids can’t understand what he had said. Obviously, A has got the message. According to the above analysis, we can conclude that there are six causes resulting in ambiguity. First, the unclear pronoun。 second, the word that has two or more meanings。 third, the word in the sentence that has more than one part of speech。 fourth, the unclear indicating target。 fifth, the indefinite structure of the sentence。 and sixth, the word itself. 4. Conclusion Ambiguity is one of the subjects that the scholars are willing to probe. It is a barrier which we should refrain from in the social munication, but as a mon phenomenon in the natural language, ambiguity exists reasonably. There are many causes that lead to ambiguity, and we can avoid the negative side of ambiguity effectively if we understand it very well. This paper analyses the ambiguity from four perspectives: phonology, lexicology, grammar and pragmatics. The linguists have studied the ambiguity for a long time, because it is not only important for munication, understanding of the language, and writing and translating, but also very important for the development of the theory of language. 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