Mark Twain's life as a writer started ________A. the best known author in American literatureB. the best author in America all the timeC. the best known author in the worldD. the best author in the worldA、his adventures on the MississippiB、his successfulway to a writerC、his life as a writerD、his successful lecturesA、Tom SawyerB、Huckleberry FinnC、Life on the MississippiD、Both A and BA、when he was a boyB、before he got marriedC、after he got marriedD、when he got married