【正确答案】正确答案：Conversational implicature as a type of implied meaning, which is deduced on the basis of the conventional meaning of words together with the context, under the guidance of the CP and its maxims. In this sense, implicature is comparable to illocutionary force in speech act theory in that they are both concerned with the contextual side of meaning, or 言外之意 in Chinese. Toward the end of his "Logic and Conversation", Grice mentioned briefly some characteristics of conversational implicature. (1) Calculability The fact that speakers try to convey conversational implicatures and hearers are able to understand them suggests that implicatures ate calculable. They can be worked out on the basis of some previous information. (2) Cancellability Cancellability is also known as defeasibility. We said that the presence of a conversational mplicature relies on a number of factors: the conventional meaning of words used, the CP, the linguistic and situational contexts, etc. So if any of them changes, the implicature will also change. For example, once Premier Zhu began his talk with a reference to MIT, saying that when he was in Tsinghua, which was known as China's MIT, he wished he could have a chance to study and get a degree at MIT some day. Now he went on, "但是，校长先生请不要误会，我绝对不是要个荣誉学位。” (3) Non-detachability By non-detachability is meant that a conversational implicature is attached to the semantic content of what is said, not to the linguistic form. Therefore it is possible to use a synonym and keep the implicature intact. In other words, an implicature will not be detached, separated form the utterance as a whole, even though the specific words may be changed. For example, with "John's an enormous intellect." we can also say "John's a genius. " (4) Non-conventionality Conversational implicature is by definition different from the conventional meaning of words. To show the differences more clearly, we can have a look at some examples of entailment, e. g. I saw a boy. I saw a child. （此题考查格赖斯会话含义的特点，共四点分别举例说明。）