Какие вещества (молекулярного или немолекулярного строения) имеют более высокие температуры плавления?

Оur planet should be  safe to live on.
Our country should be powerful and happy to live in.
Our air should be  unpolluted and clean to breathe.
Our rivers,lakes and seas should be clean and not dangerous to bathe in.
Our food should be healthy to eat.
Our forests should be rich in birds and animals.
Our peaple should be healthy and happy.
Our water should be clean and safe to drink.