It takes him two years to write the book.（改为同义句）

网友回答

He spends two years writing the book
======以下答案可供参考======
供参考答案1:
He spends two years (in) writing the book
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供参考答案2:
He spends two years (in) writing the book./He spends two years on the book.
供参考答案3:
He spends two years on the book.
He spends two years (in) writing the book.
供参考答案4:
He spends two years writing the book
spend 后跟（in）doing 结构in可以省略