第8题: [单项选择]Digging the garden with a spade is a very ______ task. I am exhausted after such two-hour's work. A. industrious B. manual C. conscientious D. laborious 参考答案:D 答案解析:[解析] D项“laborious(工作)艰苦的,费力的”符合题意。其他三项“A项industrious勤勉的,刻苦的;B项manual手工的,手动的;C项conscientious尽责的”都不正确。