dumb

/dəm/

slow to learn or understand; lacking intellectual acuity; ; ; - Thackeray

中文释义：愚蠢的；迟钝的

It was a dumb mistake to leave the keys inside the car.

把钥匙留在车里是个愚蠢的错误。

He felt dumb for not understanding the simple instructions.

他因为没理解简单的指示而觉得自己很笨。