听第10段材料，回答第17～20题。

whAt CAn wE lEArn From whAt thE spEAkEr sAiD [A] hE is A rEtirED tEAChEr oF history.[B] hE thinks ChilDrEn wErE hAppiEr in thE pAst.[C] hE livEs on A FArm FAr AwAy From CitiEs.