Manually Annotated Sub-Corpus (MASC)
（重定向自MASC）
MASC is a balanced subset of 500K words of written texts and transcribed speech drawn primarily from the Open American National Corpus (OANC). The OANC is a 15 million word (and growing) corpus of American English produced since 1990, all of which is in the public domain or otherwise free of usage and redistribution restrictions.