----Must I do well in all the subjects, Mum?
----Sure, baby! As an old saying goes, knowledge is .
A. mand
B. effort
C. power
D. energy
网友回答
A. mand
B. effort
(答案→)C. power
D. energy
解析：词义辨析。A要求，命令；B努力；C权利，力量；D能量，精力；句意：—妈妈我非在所有学科中都表现很好吗？—当然。正如谚语所说：只是就是力量。根据句意说明C正确。