18. The apparatus of claim 15 , wherein, for performing the second recognition, the processor comprises: a calculator configured to perform the evaluation of the sentence, including calculating a degree of suitability for each word in the sentence based on a relationship of each word in the sentence with other words in the sentence; a detector configured to determine the target word from among the words in the sentence based on the calculated degree of suitability for each word; and a replacer configured to replace the target word with the selected at least one of the sampled candidate words.
18. The apparatus of claim 15 , wherein, for performing the second recognition, the processor comprises: a calculator configured to perform the evaluation of the sentence, including calculating a degree of suitability for each word in the sentence based on a relationship of each word in the sentence with other words in the sentence; a detector configured to determine the target word from among the words in the sentence based on the calculated degree of suitability for each word; and a replacer configured to replace the target word with the selected at least one of the sampled candidate words. 19. The apparatus of claim 18 , wherein, in determining the target word, the detector is further configured to either one or both of identify words having a lower degree of suitability than a predetermined threshold value, and determine a predetermined number of words, in order, starting from a lowest degree of suitability for generating plural candidate sentences in order with respective target word replacements.