More than 99% of the natural uranium in the world is in this form.

世界上99%以上的天然铀都是​​这种形态。

By far the most common naturally occurring form of uranium is the isotope uranium-238. More than 99% of the natural uranium in the world is in this form.

到目前为止，最常见的天然铀形式是同位素铀 238。世界上99%以上的天然铀都是​​这种形态。