读对话，回答问题。
Tom: Hello, Mike!
Mike: Hello, Tom! Look, this is a picture of my family.
Tom: Who is she?
Mike: She is my grandmother. She's 76 years old. She is younger than my grandfather.
Tom: Is this your mother?
Mike: Yes.
Tom: What does she do?
Mike: My mother is a doctor.
Tom: How many people are there in your family?
Mike: There are five.
1. How old is Mike's grandmother?
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2. Is Mike's grandmother older than his grandfather?
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3. What does Mike's mother do?
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4. How many people are there in Mike's family?
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