used to show movement into or on a particular place

I slipped as I stepped onto the platform. 我登上站台的时候脚底一滑。

The sheep were loaded onto trucks. 羊被装上了卡车。

used about changing to, or starting to talk about, a different subject

How did we get onto this subject? 我们是怎么谈到这个话题的？

Can we move onto the next item on the agenda? 我们可以进行议程的下一项内容吗？

to keep holding something

Hold onto my hand and you'll be perfectly safe. 抓住我的手，你会十分安全的。

knowing about someone or something that can be useful to you

You're onto a good thing with this buy-one-get-one-free deal. 你碰上了好事，商店里有买一赠一的活动。

UK David put me onto (= told me about) a really good restaurant. 戴维给我介绍了一家非常好的餐馆。

knowing about something bad someone has done

He knows we're onto him. 他知道我们盯上了他。

UK Who put the police onto (= told the police about) her? 是谁向警方告发了她？

If you are onto someone, you talk to that person, especially to ask them to do something, or to complain to them.

I must get onto the plumber about the shower. 我必须找水暖工说说淋浴器的事。

Dad was onto her again about doing her homework. 爸爸又催着她做家庭作业了。

used about someone or something that is added to or joins a particular thing

Imir's been voted onto the union committee. 伊米尔被选为工会委员会的成员了。

I've been having problems loading this software onto my computer. 我一直没办法把这套软件装到我的计算机上。