whereof
adverb old use or formal uk/ˌweəˈrɒv/ us/ˌwerˈɑːv/
其，在其中
of which or what
She knows whereof she speaks (= she has direct experience or knowledge of what she is talking about). 她很清楚她说的情况是什么样。
He sees hostility, the cause whereof he does not know. 他看到了敌意，却不知道其原因。
- More examples
- I lived in New York for ten years; I know whereof I speak when it comes to roaches.
- vice that affects the public, and whereof the public has a right to complain
- Wittgenstein said: "Whereof one cannot speak, thereof one must be silent."
- punishment for crime whereof the party shall have been duly convicted
- his trim blue coat, whereof the buttons sparkled