问题补充：
Although you have learned much knowledge and a lot of theories, the problem is can be put into practice.
A. what you have learned
B. how what you have learned
C. that what you have learned
D. how that you have learned
答案：
A. what you have learned
(答案→)B. how what you have learned
C. that what you have learned
D. how that you have learned
解析：考查表语从句。本题中how引导起该表语从句，what you have learned在表语从句中做主语，what在该主语从句中做动词learn的宾语。句意：尽管你已经学会了很多知识和理论，问题是你如何把你所学的知识付诸实施。故B正确。
