1. An apparatus for automatically evaluating sentences over the internet, wherein the apparatus comprises a processor, and wherein said processor comprises: an input sentence divider configured to divide a composed input sentence received via the internet into morphemes which are the smallest units of a sentence; a part-of-speech tagging section configured to tag parts-of-speech to the morphemes; a syntax analyzer configured to analyze, based on the parts-of-speech, a syntax structure of the composed input sentence, and to output a syntax tree as an analysis result; a sentence evaluating section configured to evaluate whether the composed input sentence is grammatically correct by using the syntax tree output by the syntax analyzer; and an error detector configured to generate, by using an n-gram, a part-of-speech string for each of the parts-of-speech tagged by the part-of-speech tagging section, to detect a syntax error, by analyzing, based on a regular grammar rule and a context free grammar rule, the generated part-of-speech string, wherein the regular grammar rule and the context free grammar rule are defined in accordance with a connection relationship, and the connection relationship is between adjacent parts-of-speech among the parts-of-speech tagged by the part-of-speech tagging section, and to provide a corrected draft of the composed input sentence, wherein the corrected draft corrects the detected syntax error.