The crab's body inside the hard crust or shell is quite soft.

螃蟹硬壳里面的身体很柔软。

But how can a crab grow when it is covered all over with a hard crust?

但是，螃蟹浑身都是硬壳，怎么长大呢？

They work like snowshoes, keeping the body from breaking through the upper hard crust while allowing them unimpeded movement across the lakebed.

这些脚趾如同雪地鞋使其能够在湖床上来去自如，身体不至于压穿泥地硬壳。

At least three of the moons of Jupiter, for instance, are thought to have buried oceans under their hard crusts of ice.

例如，木星至少有三颗卫星被认为坚硬的冰壳下藏着海洋。

One idea to explain this is that the ice is porous and fluffier inside the comet, but as it nears the Sun the ice at the surface warms and changes its structure, forming that harder crust.

对于这一现象，有一种解释是，彗星内部的冰更疏松多孔，但当它靠近太阳时，彗星表面的冰变暖并改变了结构，形成了更坚硬的外壳。