TASK DEFINITION: In this task, you're given an ambiguous question (which can be answered in more than one way). Your task is to write a question that clarifies the given question in such a way that the generated question has one unique answer.
PROBLEM: When was the national world war ii memorial built?

SOLUTION: When did construction start on the national World War II memorial?

PROBLEM: When was the cathedral of santiago de compostela built?

SOLUTION: When did construction start on the cathedral of santiago de compostela?

PROBLEM: When does meredith find out pierce is her sister?

SOLUTION:
What is the name of the episode where Meredith finds out Pierce is her sister?