2.The problem was that the earth became violent because it was not clear whether the solid shape was to last or not. 问题是地球开始变得激烈动荡，不知道这个固体形状是否会继续下去。

n. 固体 solid, liquid, gas adj. 固体的；实心的,无空隙的；结实的，坚固的

solid fuels solid food a solid sphere(球体) solid furniture a man of solid build（体形格，身材）

1) Matter has three states: solid, liquid and gas.

2) When water freezes, it becomes solid and we call it ice.