Without noticing what I was doing, I took hold of the knob, and open comes the door!

我没有注意到我在做什么，我抓住门把手，门开了！

youdao

She swung around to him, spilling her tea without noticing it.

她急转过身来对着他，茶水洒了出来她都没注意到。

《柯林斯英汉双解大词典》

So far, research suggests it may be possible to learn about the tone and pronunciation of a language or even the meaning of words while sleeping, although it is to a weaker level than what we do during the day without noticing.

到目前为止，研究表明，在睡觉的时候学习一门语言的语调和发音，甚至是单词的意思是可能的，尽管这比白天无意识学习的效果要差。

youdao

"I like the plants that people walk by every day without noticing, " she said.

WSJ: Tama Matsuoka Wong, a Gourmet Harvester in the Wilds of New Jersey | Creating

The reaction underlines the depths of government unease at a protest that you could easily walk past without noticing.

BBC: Rare strike alarms Iran's leaders

Mr Yanukovich, by contrast, seems to have waded across the Rubicon without noticing.

ECONOMIST: Ukrainian justice