If someone works tirelessly, they keep going for a long time without stopping and without seeming to get tired. The word is an adverb, so it goes with a verb: you work tirelessly, campaign tirelessly, fight tirelessly.

If someone works tirelessly如果有人不知疲倦地工作，they keep going for a long time表示他們長時間持續下去，without stopping不停下來 and也 without seeming to get tired不顯得累。The word is an adverb這個字是副詞，so所以 it goes with a verb要搭配動詞：you work tirelessly你可以說work tirelessly不知疲倦地工作、campaign tirelessly不知疲倦地拉票、fight tirelessly不知疲倦地奮戰。

Two things are packed inside it. One is time: this is not one long afternoon, it is weeks, years, sometimes a whole life. The other is feeling: the person wants to do it. Nobody is forcing them.

Two things are packed inside it裡面其實包含兩件事。One is time一個是時間：this is not one long afternoon不是一個下午而已，it is weeks, years, sometimes a whole life而是好幾個星期、好幾年，有時候是一輩子。The other is feeling另一個是感覺：the person wants to do it這個人是自己想做的。Nobody is forcing them沒有人強迫他們。

That is why we say a doctor worked tirelessly to save people, and it sounds like praise. It is almost always praise, in fact. You will meet it in news stories, in speeches, in the words people say at a funeral, in a boss thanking a team. It is a slightly formal, warm word — you would write it in a card, but in ordinary talk with a friend you would more likely say "she never stops" or "he works so hard".

That is why we say這就是為什麼我們會說 a doctor worked tirelessly to save people醫生不知疲倦地工作救人，and而 it sounds like praise聽起來像是稱讚。It is almost always praise它幾乎總是稱讚，in fact事實上。You will meet it你會遇到它 in news stories在新聞報導裡、in speeches在演講裡、in the words people say at a funeral在告別式上大家說的話裡、in a boss thanking a team在老闆感謝團隊時。It is a slightly formal, warm word這是個稍微正式、帶點溫暖的字——you would write it in a card你會寫在卡片裡，but但 in ordinary talk with a friend平常跟朋友聊天 you would more likely say你比較會說 "she never stops"『她從不停下來』 or或 "he works so hard"『他好認真』。

One honest thing though: nobody is really tireless. The person does get tired. The word describes how it looks from outside — they kept going anyway. So it is a kind of gentle exaggeration that everyone accepts.

One honest thing though不過老實說一件事：nobody is really tireless沒有人真的不會累。The person does get tired這個人其實還是會累。The word describes how it looks from outside這個字描述的是從外面看起來的樣子——they kept going anyway他們還是繼續做下去了。So所以 it is a kind of gentle exaggeration這算是一種溫和誇飾 that everyone accepts大家都能接受的。

Because it carries admiration, it sounds odd with a bad action; "he worked tirelessly to ruin her life" is possible, but the speaker is being ironic on purpose, and a listener will hear that twist.

Because it carries admiration因為它帶著讚賞的意味，it sounds odd with a bad action用在壞事上會顯得奇怪；"he worked tirelessly to ruin her life"『他不知疲倦地努力去毀掉她的人生』 is possible是可能的，but但 the speaker is being ironic on purpose說話的人是故意在反諷，and而 a listener will hear that twist聽的人也聽得出這個轉折。