39.When you read the book you’d better made a mark you have any questions.A. at whichB.

问题补充：

39.When you read the book, you’d better made a mark you have any questions.

A. at which

B. at where

C. place

D. where

答案：

A. at which

B. at where

C. place

(答案→)D. where

解析：where引导地点状语从句子，意思是：读书时，你最好在有疑问的地方打上符号。