Would you be concerned if someone you loved was drinking an average of two pints of bitter a day? Or do you believe the old saying that 'another little drink won't do us any harm ? You might be more uneasy it the someone in your life was your 15-year-old daughter. Through the revealing attitudes of teenagers and their parents, Q.E.D. discovers how little all of us understand about alcohol -the third-biggest health hazard in Britain-and how widespread is the problem of under-age drinking.