At all 是個副詞片語，意為「根本，到底，無論如何，絲毫，一點兒」，係用於否定句和疑問句 (不可用於肯定句)，表示強調。例如：
- Our manager never laughed at all. (我們經理從來不笑)
- It is not so much how much he leaked out the plans of the pay cuts; the question is whether he leaks at all. (他洩漏多少減薪的計畫無關緊要；問題在於他到底有沒有洩漏)
- He hasn’t been at all well recently. (最近他的健康非常差)
- He’ll propose tomorrow if he proposes to Mary at all. (如果他真的要向瑪麗求婚的話，那麼他一定會在明天採取行動)
- Is there any possibility at all of snow tonight? (今晚真的有可能下雪嗎？)
- Is there any uncertainty at all about the way she committed suicide? (對於她自殺的方式，有沒有任何疑點呢？)
At all 可以用在形容詞之前或之後。例如：
- He was not at all surprised. (他一點也不驚訝)
= He was not surprised at all. - Her argument wasn’t at all convincing. (她的論據絲毫沒有說服力)
= Her argument wasn’t convincing at all. - Is it at all possible that John alone can drink ten bottles of beer? (難道約翰真的能一個人喝十瓶啤酒嗎？)
= Is it possible at all that John alone can drink ten bottles of beer?
At all 經常用在問句的末尾來使問句聽起來更有禮貌。例如：
- Would you like any desserts at all? (您想要甜點嗎？)
- Do you have any small change at all? (你有零錢嗎？)
我們可以使用 not at all (別客氣；一點都不) 來對 Would you mind …? 或 Do you mind (if) …? ([如果]…你介意嗎？你反對…嗎？) 這兩個常用問句以及別人對你說 thank you 的禮貌回答。例如：
- A: Would you mind turning (= please turn) your ringtone down a little please? (A：你介意將手機鈴聲調小一點嗎？ / 請你將手機鈴聲調小一點好嗎？)
B: No, not at all. (B：不，一點都不) - A: Do you mind if I (= May I) use your computer? (A：你介意我用你的電腦嗎？)
B: Not at all. (B：一點都不) - A: Thank you for your help. (A：感謝您的幫忙)
B: Not at all. (B：不客氣) - A: It’s very kind of you to help me, thank you. (A：承蒙惠助，不勝感激)
B: Not at all. (B：別客氣)