Final answer:
Iago thinks he should have been made lieutenant because he has more practical military experience than Cassio and is resentful of Cassio's academic appointment.
Step-by-step explanation:
Iago, a character in William Shakespeare's play Othello, believes he should have been made lieutenant instead of Cassio for several reasons. Iago feels he has more military experience and a better understanding of the soldier's life, which contrasts with Cassio's more academic background and theoretical knowledge. Moreover, Iago is resentful and envious of Cassio's appointment, believing he has been wronged by Othello, which fuels his subsequent betrayal and the tragic events of the play.