题目

Every boy and every girl ______ that each day and each hour brings ______ duty. A．know；their  B．knows；their C．knows；its   D．know；its   答案： C   此题考查主谓一致。“every/each＋单数名词＋and＋every/each＋单数名词”作主语时，谓语动词用单数形式。  

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