It is well known that knowledge is treasure house but practice is key to it.A. a; theB.

问题补充：

It is well known that knowledge is treasure house, but practice is key to it.

A. a; the

B. the; the

C. a; x

D. x; the

答案：

(答案→)A. a; the

B. the; the

C. a; x

D. x; the

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