"Thereby" means "and by doing that" — it links an action to the result that the action itself produces. Its favourite shape is "thereby + -ing": "The company moved production to Vietnam, thereby cutting its costs by half." That means: the moving is what cut the costs. It is not just "and then"; it says the first thing was the METHOD of the second.

"Thereby" means "and by doing that""Thereby"的意思是「藉由這麼做」 it links an action to the result that the action itself produces它把一個動作跟這個動作本身造成的結果連在一起。Its favourite shape is "thereby + -ing"它最常見的形式是"thereby + -ing" "The company moved production to Vietnam, thereby cutting its costs by half.""The company moved production to Vietnam, thereby cutting its costs by half." That means: the moving is what cut the costs這句話的意思是：搬遷這個動作本身就是讓成本減半的原因。It is not just "and then"它不只是"and then"（然後） it says the first thing was the METHOD of the second它說的是前面那件事是後面那件事的「方法」。

Compare "so" or "therefore", which only say one thing followed from another. It is formal and written — reports, essays, legal writing, news analysis.

Compare "so" or "therefore,"對比"so"或"therefore" which only say one thing followed from another這兩個字只說一件事接在另一件事後面發生。It is formal and written它是正式的書面用語 reports, essays, legal writing, news analysis用在報告、論文、法律文件、新聞分析裡。

In speech people say "and that way", "and so", or just start a new sentence: "...and that cut costs by half." There is also one famous fixed phrase you will meet in stories and articles: "thereby hangs a tale", which means "there is an interesting story behind that" — it comes from Shakespeare and is used with a smile, not literally.

In speech people say "and that way", "and so,"口語裡人們會說"and that way"、"and so" or just start a new sentence: "...and that cut costs by half."或乾脆重新起一句："...and that cut costs by half." There is also one famous fixed phrase you will meet in stories and articles還有一個你會在故事和文章裡遇到的知名固定片語 "thereby hangs a tale,""thereby hangs a tale" which means "there is an interesting story behind that"意思是「這背後有個有趣的故事」 it comes from Shakespeare and is used with a smile, not literally它出自莎士比亞，帶著笑意使用，不是字面上的意思。