Twain was restless when he was young and moved a lot, first eastward as a journeyman printer, up and down （）as a steamboat pilot.
A、the Mississippi
B、the Back River
C、the Firesteel River
D、the Bark River
【正确答案】：A
【题目解析】：马克·吐温童年的许多经历发生在密西西比河流域，这也成为他许多小说主要描写的地方，比如The Adventures of Tom Sawyer《汤姆·索亚历险记》(1876)，The Adventures of Huckleberry Finn《哈克·费恩历险记》(1884)。
