Definition: into a bus, train, plane, etc. or onto a horse Level: B1
当我正要上火车时，火车突然开动了。
The train suddenly started moving as I was stepping ___on.
她一骑上马，马就开始动了。
Her horse began to move as soon as she was ___on.
我们需要在公共汽车离开前上车。
We need to get ___on the bus before it leaves.
