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Complete the teenager's interview questions for her grandfather's history project.
"Grandpa, _________________________ memorize all of your friends' phone numbers? And where ____________________________ for fun before the internet was invented?"
"Grandpa, did you use to memorize all of your friends' phone numbers?"
To form a question about a past habit, we use Did + subject + use to + base verb. Because "did" handles the past tense, we use "use" without the "d".
"And where did you use to go for fun before the internet was invented?"
Even with question words like "where," the rule stays the same: Wh- word + did + subject + use to.