The stairs is one of the greatest inventions of human beings。
We use them everyday and we can see them everywhere.
But do you konw the history of the stairs?
Now let me tell you about that............
I don't know what the first stairs looked like,
because at that time there must have been no camera.
But next picture maybe can help us to remember
something.
Yes, This Is It!~!~
It even was used in the war...
And then, the people maybe think it was a little dangerous,
so, they gave it two banisters.
Although sometimes it is not needed .....
Stairs are art：
This one is a little special .
Even toys：
Sometimes you will feel climbing is very tiring ，
Intelligent human with the development of science and technology,
They invented the escalator.
In high-rise buildings, they also invented the elevator ：
In the end, I'd like to show you people's imagination is how great，
Let's watch video of what they did.......
