How to say sir in French?

The French way of saying "Sir":

1. monsieur

2. Sire

3. sidi

1. Monsieur in a sentence

Un monsieur vous attend dans le hall. A gentleman is waiting for you in the hall

2. Sire in a sentence

Sire, je vous demande la permission de les suivre. ? Sir, I ask your permission to travel with them

3. sidi in a sentence

M. Sidi Mohamed Ould Boubacar, Premier Ministre de la République Mr. Sidi Mohamed Ould Boubacar was escorted to the rostrum.