What’s the best age to start learning a foreign language?
What’s the best age to enter university?
What’s the best age to allow driving a car?
What’s the best age to allow voting?
What’s the best age to allow drinking alcohol?
What’s the best age to allow smoking?
What’s the best age to get married?
What’s the best age to have children?
What’s the best age to start a career?
What’s the best age to make a career change?
What’s the best age to retire?
What’s the best age to die?