1.in addition 另外，此外
There is, in addition, one further point to make.
此外，还有一点要说。

2.billions of years 数十亿年
Astrogeologists suspect that these scarps having formed billions of years ago as the planet's surface cooled and shrank.
太空地质学家猜测这些陡坡是在几十亿年前当行星表面冷却收缩时开始形成的。