“Simpler” books are the foundation students build a lifelong habit of reading and further

问题补充：

“Simpler” books are the foundation students build a lifelong habit of reading and further the actual skill of reading for longer and stronger periods of time.

A. which

B. upon which

C. for which

D. in which

答案：

A. which

(答案→)B. upon which

C. for which

D. in which

解析：考查介词加关系代词引导的定语从句。the foundation是先行词，定语从句缺少状语，以……为基础，要用on/upon the foundation结构，所以选B。