in 同 on 的分別...

沒有一個簡單規則，只能多看多記。給你一些例子：

in the car
on the bus
on the plane

I am lying in the sun.
I am lying on the floor.

He has arrived on time. 他準時到達。（例如約了十時見面，他在九時五十分來到。）
He has arrived in time. 他及時到達。（約了十時，他真的在十時正來到。）

He is lying on the bed.
He is lying in the bed. (Both are correct. When you say in the bed, you imply you are wrapping yourself with a blanket. When you say on the bed, you imply you are just lying on it.)

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