We only have one earth, but this unique earth is not simple. There are many things need people to understand, to solve.

We only have one earth, but this unique earth is not simple. There are many things need people to understand, to solve.

In North, when winter comes, the weather is very cold, the cloud covers the sunshine all the time, it is hard for peopl

In North, when winter comes, the weather is very cold, the cloud covers the sunshine all the time, it is hard for peopl