Dites quand il faut traduire it is par il est^ et

quand il faut rendre ces mots par c'est. Expliquez la différence entre les deux phrases : "^s^il mon frère? Est-ce mon frère ?^^ et traduisez comme exemples:

"It is noble to die for one's country. It is a noble thing to die for one's country. Is it you ? It was not an officer who was killed, but a private. Is it true that you hâve been very ill? Yes, it is true."