8. The method of text script generation for a corpus-based text-to-speech system according to claim 1 , said method presents at least unit-type covering rate and unit-type hit rate as a first performance index and a second performance index respectively, for the text script generation in the corpus-based text-to-speech system.
10. The method of text script generation for a corpus-based text-to-speech system according to claim 8 , wherein said unit-type hit rate is defined as r H =  X ′   X  , X is the set of all unit instances in said source corpus, and X′ is the set of all unit instances gathered by the set of unit types covered by the set of all unit instances in the selected text script.