我在看單字的例句
忽然忘記這個文法技巧
想問是那裡的
A murderer is, by definition , one who intentionally kills another person.
請問整句逗點怎麼來的
謝謝你

這就單純是副詞插入的用法，你可以移到句中，例如：He,however, doesn't like the way she handle the situation.

Our help, however small it may be, could mean a lotto others.

Galavant: My time, at last, has come!

菜逼八，多寫考題，仔細看題目、文章裡常常都有