Whereby means 'by which' or 'through which' — it points back to a thing just named and says that this is the method, the arrangement, or the rule that makes something happen. It almost always sits right after a noun like system, plan, agreement, law, deal, process, arrangement: 'a scheme whereby students can pay in ten instalments' means 'a scheme through which they can pay that way'.

Whereby means 'by which' or 'through which'Whereby意思是「by which」或「through which」——it points back to a thing just named它指回剛剛提到的東西，and says that this is the method, the arrangement, or the rule that makes something happen說這就是讓某件事發生的方法、安排，或規則。It almost always sits right after a noun like system, plan, agreement, law, deal, process, arrangement它幾乎都緊接在system、plan、agreement、law、deal、process、arrangement這類名詞後面：'a scheme whereby students can pay in ten instalments'「a scheme whereby students can pay in ten instalments」means 'a scheme through which they can pay that way'意思是「a scheme through which they can pay that way」。

It belongs to formal written English — contracts, rules, official reports, news writing, academic papers. Spoken English would say 'a scheme where you can pay in instalments' or 'a scheme that lets you pay in instalments'.

It belongs to formal written English它屬於正式的書面英文——contracts, rules, official reports, news writing, academic papers合約、規章、官方報告、新聞寫作、學術論文。Spoken English would say口語英文會說 'a scheme where you can pay in instalments'「a scheme where you can pay in instalments」，or 'a scheme that lets you pay in instalments'或「a scheme that lets you pay in instalments」。

Unlike whence and wherefore, whereby is not dead or funny; it is alive and normal in serious documents, and a lawyer or a journalist will write it today without a second thought. It cannot start a question — you cannot ask 'Whereby did you do it?' It only joins one part of a sentence to another.

Unlike whence and wherefore跟whence和wherefore不一樣，whereby is not dead or funnywhereby並不是死掉或可笑的字；it is alive and normal in serious documents它在正式文件裡活著、很正常，and a lawyer or a journalist will write it today without a second thought律師或記者今天寫到它時，不會多想一下。It cannot start a question它不能放在句首問問題——you cannot ask 'Whereby did you do it?'你不能問「Whereby did you do it?」It only joins one part of a sentence to another它只負責把句子的一部分和另一部分連起來。

One caution: in careless modern writing some people use whereby loosely to mean 'in which' or 'and as a result', but its real job is to name the means.

One caution有一點要小心：in careless modern writing some people use whereby loosely to mean 'in which' or 'and as a result'在不夠嚴謹的現代寫作裡，有些人會鬆散地用whereby來表示「in which」或「and as a result」，but its real job is to name the means但它真正的功能是點出方法、手段。