[For goodness sake! This is Romeo and Juliet! There are about a million quotes that show passion! That being said, there are many different types of passion, so let me choose a couple of good ones for you:]
Alive in triumph, and Mercutio slain? / Away to heaven respective lenity, / And fire-eyed fury be my conduct now! (3.1.122-124)
Here Romeo shows his heartfelt passion for his slain friend, Mercutio. Unfortunately, he turns his passion into murder. Killing Tybalt and being banished from Verona as a result are two plot points that deftly bring about Romeo's eventual end.
Be not so long to speak. I long to die / If what thou speakst speak not of remedy. (4.1.68-69)
You will find that much of Juliet's show of passion has to do with desperation in regards to her situation (and that many of the passionate quotes from the play are from Act 5). Here Juliet begs Friar Laurence for a remedy to the lovers' desperate situation. Longing to die, wishing for suicide, and eventually carrying the act out are all through the passion of desperation.
O my love! my wife! / Death that hath sucked the honey of thy breath, / Hath had no power yet upon thy beauty. / Thou art not conquered. (5.3.91-94)
Here is a "usual" show of passion from Romeo in that he is expressing his love for Juliet. The difference here is that Juliet is no longer alive (or so Romeo thinks), but Romeo's passion is no less amazing.
O churl! Drunk all, and left no friendly drop / To help me after? / . . . O happy dagger! This is thy sheath; there rest, and let me die. (5.3.168-175)
Juliet's last act: perhaps the biggest show of passion in the play. Juliet has gone from the passion of desperation to passion and virtual joy in death. "For never was a story of more woe / Than this of Juliet & her Romeo." (5.3.323-324)