1. 到…之上；向…之上
    If something moves or is put onto an object or surface, it is then on that object or surface.

    e.g. I took my bags inside, lowered myself onto the bed and switched on the TV...
           我把包拎进屋，往床上一倒，然后打开了电视机。
    e.g. Smear Vaseline on to your baby's skin to prevent soreness.
           给孩子皮肤上抹些凡士林以防止肿痛。

2. 到（某处）
    You can sometimes use onto to mention the place or area that someone moves into.

    e.g. The players emerged onto the field...
           运动员入场了。
    e.g. ...when the photographer sets off onto the moors...
           摄影师动身踏入高沼时

3. （光线或视线）朝向,转向
    You can use onto to introduce the place towards which a light or someone's look is directed.

onto的反义词

    e.g. ...the metal part of the door onto which the sun had been shining...
           在阳光照耀下闪闪发亮的门的金属部分
    e.g. The colours rotated round on a disc and were reflected onto the wall behind.
           圆盘上色彩流转，反射到后面的墙上。

4. 通向（某处）
    You can use onto to introduce a place that you would immediately come to after leaving another place that you have just mentioned, because they are next to each other.

onto是什么意思

    e.g. ...windows opening onto carved black-wood balconies...
           开向黑檀雕花阳台的窗户
    e.g. The door opened onto a lighted hallway.
           这扇门通往亮着灯的走廊。

5. （重心移动）到（身体某部位）上
    When you change the position of your body, you use onto to introduce the part your body which is now supporting you.

    e.g. As he stepped backwards she fell onto her knees, then onto her face...
           他向后退时，她双膝跪倒在地，接着迎面倒了下去。
    e.g. Puffing a little, Mabel shifted her weight onto her feet...
           梅布尔喘了口气，把身体重心移到脚上。

6. 到（交通工具）上
    When you get onto a bus, train, or plane, you enter it in order to travel somewhere.

    e.g. As he got on to the plane, he asked me how I was feeling...
           他上飞机时问我感觉如何。
    e.g. Who can fold up a pushchair, toddler and shopping and then get them all onto the bus?...
           谁有那本事一手收起婴儿推车，一手抱着刚会走路的孩子，还得提着刚买的东西，然后挤上公共汽车？

7. （用于 hold，hang，cling 等动词后，表示抓紧或牢牢固定）在…上
    Onto is used after verbs such as 'hold', 'hang', and 'cling' to indicate what someone is holding firmly or where something is being held firmly.

    e.g. The reflector is held onto the sides of the spacecraft with a frame...
           反射器通过支架牢牢地固定在航天器的侧面。
    e.g. She was conscious of a second man hanging on to the rail...
           她意识到还有第二个人紧紧抓着栏杆。

8. 转到（其他话题）
    If people who are talking get onto a different subject, they begin talking about it.

    e.g. Let's get on to more important matters...
           咱们谈谈更重要的事吧。
    e.g. So, if we could just move onto something else?
           那么我们可不可以干脆谈点别的？

9. 成为（列表、系统等）的一部分
    You can sometimes use onto to indicate that something or someone becomes included as a part of a list or system.

    e.g. The Macedonian question had failed to get on to the agenda...
           马其顿问题没能列入议事日程。
    e.g. The pill itself has changed a lot since it first came onto the market...
           该药片本身自首次进入市场以来已经有了很大改变。

10. 即将发现（重要之事）
    If someone is onto something, they are about to discover something important.

    e.g. He leaned across the table and whispered to me, 'I'm really onto something.'...
           他从桌上俯过身来对我低声说道：“我真的就快有重大发现了。”
    e.g. Archaeologists knew they were onto something big when they started digging.
           考古学家在发掘之初就知道他们将有重大发现。

11. 发现（某人做坏事）；对…觉察；对…知悉
      If someone is onto you, they have discovered that you are doing something illegal or wrong.

onto是什么意思

      e.g. He did not want Pollard to become suspicious that he was now onto him...
             他不想让波拉德怀疑他已察觉到其不轨行为。
      e.g. I had told people what he had been doing, so now the police were onto him.
             我已将他的所作所为告诉了别人，因此现在警方正在追查他。