n.楼梯;(楼梯的)一级;
例句:
We had to carry the piano up three flights of stairs .
我们不得不抬着钢琴上了三段楼梯。
I followed her down the stair.
我跟着她下了楼梯。
The children ran up/down the stairs .
孩子们跑上 / 跑下楼去。