{急!!!} 點樣用英文形容呢個情況?

我見到有個人上到巴士坐低左成塊面就即刻貼著個窗望出去出面...
I saw a person get on a bus. As soon as s/he sat down,
s/he pressed his/her face to the window and looked out of it.

I saw a person GET ON <----------( I saw the complete action)
I saw a person GETTING ON <-------( I saw a part of the action)
In English, we say " to get on the/a bus" and " to get in the/a taxi"

Don't say " you get on a taxi"!!!!!
When you say that, it means you will be on top of the taxi.

I saw a person got on the bus, and as soon as he sat down he looked at the outside with his face stuck on the window.