【答案解析】The sentence meaning is usually directly predictable from the grammatical and lexical features of the sentence. It is often studied as the abstract, intrinsic property of the sentence itself in terms of predication; therefore, it is abstract and de-contextualized.
A sentence becomes an utterance when it is actually uttered by people in the course of communication, and an utterance should be considered in the situation in which it is actually uttered or used.
The speaker meaning, also called the utterance meaning, is the meaning a speaker conveys by using a particular utterance in a particular context of situation. It is based on sentence meaning, and is the realization of the abstract meaning of a sentence in a real situation of communication or simply in a context; utterance meaning is richer than sentence meaning; it is identical with the purpose for which the speaker utters the sentence. Therefore, it is concrete and context-dependent.
Take the sentence "My bag is heavy" as an example. Semantic analysis of the meaning of the sentence results in the one-place predication BAG ( BEING HEAVY). Then a pragmatic analysis of the utterance will reveal what the speaker intends to do with it. How it is to be understood depends on the context in which it is uttered and the purpose for which the speaker utters it.