people cannot but ___puzzzled,for they simply cannot understand ...

问题描述:

people cannot but ___puzzzled,for they simply cannot understand ...
(上接)how he could have made such a stupid mistake
feel
feeling
to feel
having felt 请问选哪个 求详解

答案为A,因为cannot but 后接动词原形.如:
I cannot but admire him.我不得不佩服他.
Seeing the boy’s funny face,I could not but laugh.看到那孩子的滑稽面孔,我禁不住笑了.