What the boy wants ( ) a toy, and what his younger sister wants ( ) some storybooks.A. are;areB. is;isC. is;areD. are;is

本题考查主谓一致的知识点。解题的关键在于判断主语“what the boy wants”和“what his younger sister wants”所代表的内容是单数还是复数，从而确定谓语动词的形式。

对于 “What the boy wants”

• “What the boy wants” 是一个主语从句，它所表达的核心内容是 “男孩想要的东西”，在语义上是一个整体，是单数概念。
• 根据主谓一致原则，当主语是单数时，谓语动词要用单数形式。所以 “What the boy wants” 对应的谓语动词应该用 “is”。

对于 “what his younger sister wants”

• “what his younger sister wants” 同样是主语从句，其表达的是 “他妹妹想要的东西”，这里妹妹想要的是 “一些故事书”，“一些故事书” 是复数概念。
• 按照主谓一致原则，当主语是复数时，谓语动词要用复数形式。所以 “what his younger sister wants” 对应的谓语动词应该用 “are”。