今天的问题：on the bed, in bed, in the bed

On the bed 是指你在被子上盖着被子

，玩电脑，玩手机等
'A child is jumping on the bed'

In the bed 在床上，被子下，'the' 给我的感觉是你想强调这张床.
'I was in the bed, as it broke'

In bed 是指你等一下想睡了，或者你刚睡醒了，还没醒来了。
'I don't want to go out drinking, I'm already in bed'

这样理解清楚吗？