He bought a book about the____of English grammar.(know)

He bought a book about the____of English grammar.(know)
He bought a book about the____of English grammar.(know)

He bought a book about the____of English grammar.(know)
knowledge 知识

knowledge

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knowlege
他买了本有关英语语法知识的书

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knowledge 知识

knowledge

kownledge(the kownledge of关于……的知识 )