Final answer:
In Canto XIX, Virgil shows his pleasure with Dante's progress by expressing admiration and flattery towards him.
Step-by-step explanation:
In Canto XIX of Dante's Divine Comedy, Virgil shows his pleasure with Dante's progress through his reaction to Dante's encounter with Caiaphas, the high priest who played a pivotal role in Jesus' crucifixion. Virgil becomes visibly pleased with Dante when he observes that Dante's understanding of the situation exceeds his own. Virgil's pleasure is shown through his expression of admiration and flattery towards Dante.