问题补充：
There are so many good books. I really don’t know .
A. to choose which one
B. choose which one
C. to which one choose
D. which one to choose
答案：
A. to choose which one
B. choose which one
C. to which one choose
(答案→)D. which one to choose
解析：特殊疑问词+to do sth，疑问代词+to do ，故选答案为D
