7. A computer-implemented method of establishing a Chinese language punctuation model from a training corpus of Chinese sentences having a plurality of punctuation marks, comprising: at a computer having one or more processors and memory for storing programs to be executed by the one or more processors: identifying, within the training corpus of Chinese sentences having the plurality of punctuation marks, a plurality of expressions, each of the plurality of expressions including one or more Chinese characters, wherein the plurality of expressions are separated and grouped by a plurality of punctuation marks that are located at predetermined locations in the training corpus of Chinese sentences; grouping the plurality of expressions in the training corpus of Chinese sentences into a plurality of characteristic units according to semantic features of the plurality of expressions and predefined characteristic templates of the plurality of characteristic units, each characteristic unit including a respective series of expressions and a unique identification number assigned to the characteristic unit; and for each of the plurality of characteristic units, recording a respective frequency of occurrence for each of the plurality of punctuation marks appearing in the corresponding series of expressions found in the training corpus of Chinese sentences; and wherein a plurality of probabilities for a plurality of punctuation marks associated with each of the plurality of characteristic units are used to determine a punctuation mark for a corresponding characteristic unit found in a Chinese sentence extracted from a speech input through speech recognition and that is not yet segmented by punctuation marks; determining a punctuation mark and its weight for each of a plurality of expressions in a Chinese sentence according to a plurality of possible punctuation marks extracted from the Chinese language punctuation model; calculating an overall weight for each possible arrangement of punctuation marks in the Chinese sentence based on the weights of punctuation marks at each of the plurality of expressions in the Chinese sentence; and adding the punctuation marks corresponding to an arrangement of a maximum overall weight into the Chinese sentence.
7. A computer-implemented method of establishing a Chinese language punctuation model from a training corpus of Chinese sentences having a plurality of punctuation marks, comprising: at a computer having one or more processors and memory for storing programs to be executed by the one or more processors: identifying, within the training corpus of Chinese sentences having the plurality of punctuation marks, a plurality of expressions, each of the plurality of expressions including one or more Chinese characters, wherein the plurality of expressions are separated and grouped by a plurality of punctuation marks that are located at predetermined locations in the training corpus of Chinese sentences; grouping the plurality of expressions in the training corpus of Chinese sentences into a plurality of characteristic units according to semantic features of the plurality of expressions and predefined characteristic templates of the plurality of characteristic units, each characteristic unit including a respective series of expressions and a unique identification number assigned to the characteristic unit; and for each of the plurality of characteristic units, recording a respective frequency of occurrence for each of the plurality of punctuation marks appearing in the corresponding series of expressions found in the training corpus of Chinese sentences; and wherein a plurality of probabilities for a plurality of punctuation marks associated with each of the plurality of characteristic units are used to determine a punctuation mark for a corresponding characteristic unit found in a Chinese sentence extracted from a speech input through speech recognition and that is not yet segmented by punctuation marks; determining a punctuation mark and its weight for each of a plurality of expressions in a Chinese sentence according to a plurality of possible punctuation marks extracted from the Chinese language punctuation model; calculating an overall weight for each possible arrangement of punctuation marks in the Chinese sentence based on the weights of punctuation marks at each of the plurality of expressions in the Chinese sentence; and adding the punctuation marks corresponding to an arrangement of a maximum overall weight into the Chinese sentence. 11. The method of claim 7 , wherein the series of Chinese expressions associated with a characteristic unit only includes a single Chinese expression, and the corresponding characteristic unit defines a position of the single Chinese expression in the training corpus of Chinese sentences and semantic features of the single Chinese expression.