问题补充：
The question is can be put into practice.
A. how you have learned
B. how what you have learned
C. that why you have learned
D. how that you have learned
答案：
A. how you have learned
(答案→)B. how what you have learned
C. that why you have learned
D. how that you have learned
解析：考查名词性从句。此句话是一个表语从句，表语从句的主语为what引导的主语从句。选项中you have learned后缺少宾语，故用的what，句意：问题就是你如何把你所学的东西用到实践中。所以选B。
