"Run down the stairs" is the phrase used to describe the act of moving quickly down a set of stairs.
The origins of the phrase are straightforward and reflect the physical motion involved. It is a combination of the verb "run" which refers to moving quickly, and the preposition "down" which specifies the direction of the movement. The word "stairs" refers to the staircase being descended.
Here are some examples of the phrase in context:
"I had to run down the stairs to catch the train."
"She tripped and fell as she was running down the stairs."
"He took two steps at a time as he ran down the stairs."
以上的例句分别翻译为：
"我必须跑下楼梯，以赶上火车。"
"她在跑下楼梯时绊倒了摔倒了。"
"他跑下楼梯时一步跨两级。"