dumb as a stump--------呆若木鸡（俚语）

英文释义
(SLANG) Describing the condition of being extremely stupid.

例句
Some of the questions I was asked in my job interview yesterday were so difficult that I felt dumb as a stump when I attempted to answer them.
昨天的求职面试有些问题实在太难，我在回答的时候呆若木鸡。