I know the reason whereat you are displeased.
我知道你为什么不快.
《现代英汉综合大词典》
I know the things whereat you are displeased.
我知道你所不高兴的是什么.
辞典例句
He turned to leave, whereat she began to weep.
他转身离开, 当下她开始哭了起来.
互联网
Whereat was he offended?
他为何生气?
互联网
"this is a statement whereat the listeners may get angry"
"we were at a party whereat there was lots of dancing"