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？)