20. The system according to claim 19 , wherein: the fluency feature is selected from the group consisting of a total number of phrase boundaries, a silence duration of a phrase boundary, a number of repetition times of a word, and a phone hesitation degree; and the phone hesitation degree includes a metric selected from the group consisting of a total number of phone hesitations and a phone hesitation duration.
19. The system according to claim 17 , wherein: the instructions, when executed, further cause the system to acquire input text data corresponding to the input speech data, and align the input text data with the input speech data.