By the time you finish the book you more about Chinese history.A. will learnB. have lear

问题补充：

By the time you finish the book, you more about Chinese history.

A. will learn

B. have learnt

C. will have learnt

D. are learning

答案：

A. will learn

B. have learnt

(答案→)C. will have learnt

D. are learning

解析：考查时态。By与完成时连用。当by后面是过去的时间，使用过去完成时；当by后面是现在的时间，使用现在完成时，当by后面是将来的时间的时候，使用将来完成时。本题By后面的时间状语从句the time you finish the book用一般现在时代替将来时，所以主句使用将来完成时。故C正确。