The reason why humming birds need long beaks is to be able to get the nectar from the flowers, kind of like how we need straws to drink out of to go cups. Humming birds also have very long tongues that also help this process. Since humming birds beaks help them get the food they need, it makes them more successful in their environment.
On the phase diagram, conditions of pressure and temperature, at which two phases coexist in equilibrium are separated by a line.
