准确的地点用 at - at the front desk, at my desk, at the entrance
在里面用 in - in his office, in the conference room, in the taxi
在上面用 on - on the bus, on the train, on the 8th floor (on 的概念是在上面可以走来走去的)
追问那么在比较大的地方呢?如果一个句子有一个大地方、一个小地方,该用哪个介词?
追答大地点的话用in,小地点用at,当然也要看具体的情况了