Mark Twain was restless when he was young and moved a lot, first

Mark Twain was restless when he was young and moved a lot, first eastward as a journeyman printer, up and down the Mississippi as__________.
A、a steamboat pilot
B、a guard
C、a servant
D、a sailor
【正确答案】：A
【题目解析】： 马克•吐温(Mark Twain)曾在印刷厂当学徒，当过送报员和排字工，后来又在密西西比河上当水手和舵手。