物质以三种形态存在：固态、液态和气态。

Matter exists in three states: solid, liquid and gas.

《新英汉大辞典》

和水类似，甲烷也有固态、液态和气态三种形态。

Like water, methane can be a solid, liquid, or gas.

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无论处于固态、液态或气态，水的化学成份都保持不变。

The chemical composition of water remains constant whether it is in solid, liquid or gaseous state.

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And the triple point of water is 16K that temperature and pressure - there's a unique temperature and pressure where water exists in equilibrium between the liquid phase, the vapor phase, and the solid phase.

与水的三相点,我们定义它为273。,水的三相点,是一个特定的温度和压强,可以使水的液态，气态和固态三相共同达到平衡，三相点是液态。

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