A teacher was giving her pu- pils a lesson on logic(逻辑).“Here is the situation(情景),”she said,“a man is stand- ing up in a boat in the middle of a river,fishing.He loses his bal- ance(平衡),falls in,and begins splashing(泼水)and yelling(叫喊)for help.His wife hears the commotion(喧闹),knows that he can’t swim,and runs down to the bank (河岸).Why did she run to the bank?” A girl raised her hand and asked,“To draw out(提取)all of his savings(存款).”