Uranus is an ice giant with a small rocky core and a thick mantle of ammonia, water, and methane.

天王星是巨星，有个小岩石内核和层由氨、水和甲烷成的厚厚的地幔。

It was probably composed of methane, ammonia, water, and hydrogen—no free oxygen was present.

它可能由甲烷、氨、水和氢成——游离氧。

Today you learned that Uranus and Neptune are ice giants, with small rocky cores, thick mantles of ammonia, water, and methane, and atmospheres that make them look greenish and blue.

今天你学到了天王星和海王星是巨星，有小的岩石内核，有由氨、水和甲烷成的地幔，以及使它们看起来呈绿色和蓝色的大气层。