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】：教材477第二段。马克?吐温少时就为生计而奔波，先是到东部当印刷工，后在密西西比河上做领航员。
