We can no longer change either the pressure or the temperature independently and stay on the boundary line where liquid and solid phases of water coexist in equilibrium.
(We; can change independently; T:no longer) (We; stay; on the boundary line) (liquid and solid phases of water; coexist; L:in equilibrium; L:the boundary line)
We We liquid and solid phases of water
can change independently stay coexist
T:no longer
on the boundary line
L:in equilibrium L:the boundary line