正如我们所知道的, 这不是容易建立一颗人造卫星.

As we know, it is not easy to build a satellite.

正如我们所知道的, 空气污染对地球和我们自己造成恶劣影响.

As we now know, air pollution is bad for the earth and ourselves.

正如我们所知道的，物质随着温度的增加和减少而膨胀和收缩。

As we know, materials expand and contract with the increase and decrease of temperature.

正如我们所知道的，落在屋顶的雨滴比落在街上的雨滴要小一些。

It is well known that the rain-drops on the roof are smaller than those that fall on the street.

正如我们所知道的那样，感恩节已经成为了一个国际性的节日。（as引导的从句修饰前面的主句，放在句后）

A.Thanksgiving day has been a international festival,as we know.