Final answer:
Eliza's quick temper is evident in the dialogue "You ought to be stuffed with nails, you ought. (flinging the basket at his feet) Take the whole blooming basket for sixpence."
Step-by-step explanation:
The piece of dialogue that shows Eliza's quick temper in the excerpt from George Bernard Shaw's Pygmalion is: "You ought to be stuffed with nails, you ought. (flinging the basket at his feet) Take the whole blooming basket for sixpence." This dialogue demonstrates Eliza's quick temper through her angry outburst and the aggressive action she takes by throwing the flower basket at Higgins' feet. It shows that she is easily provoked and has a fiery personality.