How would you use introvert in a sentence?

Here are a few examples:

"John, clearly the introvert of the group, wasn't very comfortable voicing his opinions during the meeting."

"Undoubtedly an introvert, Einstein spent a good deal of time in solitude developing theories that would change physics forever."

"Jim, ever expressive and eager to interact, was frustrated to be at the party with such a quiet and reserved introvert like Bill, whom he saw as something of a 'drag'."