题目内容：
根据材料，回答问题。Food is very important．Everyone needs to___ 21 ___ well if he or she wants to have a strong body．Our minds also need a kind of food．This kind of food is___22___．We begin to get knowledge even___23___we are very young．Small children are___24 ___ in everything around them．They learn ___25___while they are watching and listening．When they are getting older,they begin to ___26___story books，science books…，anything they like．When they find something new，they love to ask questions and___27___ to find out answers．What is the best___28___ to get knowledge?If we learn by ourselves，we will get___29___knowledge．If we are___30___ getting answers from others and do not ask why，we will never learn well．When we study in the right way，we will learn more and under- stand better．
21． A．sleep
B．read
C．drink
D．eat
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答案解析：