stair,楼梯，case,箱子，框架。

1. America'sFirst Lady stood on the sweeping staircase of the White House.

美国第一夫人站在白宫的弧形楼梯上。

2. She climbed the staircase cautiously, holding fast to the rail.

她紧紧地抓着栏杆，小心翼翼地爬楼梯。

3. She heard the priest's familiar, flat footfall on the staircase.

她听到楼梯上传来牧师那熟悉的单调脚步声。

4. He followed her up a rickety staircase to a squalid bedsit.

他跟着她上了一段摇摇晃晃的楼梯，来到了一间邋遢的卧室起居室两用房间。

5. Five firemen narrowly escaped death when a staircase collapsed beneath their feet.

他们脚下的一段楼梯坍塌时,5名消防队员险些丧命。