1·You could sit over there, by the window. There's a vacant seat.
你可以坐那儿，靠着窗户。那儿有一个空位。
2·I understand your problem and I'll see if there is a vacant seat for you. Please take this seat temporarily.
我理解你，我替您去看看是否有空位，请暂时坐这个位置。
3·Sorry, Sir. There is no vacant seat in the first class.
对不起，先生。头等舱已经没有空位了。
4·The young man elbowed the old lady aside and jumped onto the bus to occupy the vacant seat.
那小伙子将老太太推到一边，窜上车抢占了那个空位。