1. An automatic speech translation system, the system comprising: a speech recognizer configured to extract speech features from an input speech signal in a first language and to form an input language table, the input language table including an input sentence template selected by the speech recognizer from a set of sentence templates, a word class of the input sentence template, and tags showing whether each sentence element of the input sentence template is identified in the extracted speech features, the input sentence template being one of the set of sentence templates that is most closely corresponding to the input speech signal and composed of sentence elements having corresponding sentence elements in a second language; a language translator configured to receive the input language table from the speech recognizer, and to generate a translated language table corresponding to the input language table, wherein the translated language table includes a translated sentence template corresponding to the input sentence template and a translated word corresponding to a word in the word class, and the translated sentence template is composed of the corresponding sentence elements in the second language and; a speech synthesizer configured to synthesize an output speech signal based on prosody data corresponding to the translated sentence template.