Teacher：“I have two questions，it isn't necessary to answer the second question if you know the result of the first question.How much hair do you have?”
老師：“我有兩個(gè)題目，你若能答出第一題就不需答第二題。你有多少根頭發(fā)?”

Student ：“A hundred and twenty millions.”
學(xué)生：“1.2億根?！?/div>

Teacher：“How do you know it?”
老師：“你怎么知道?”

Student：“It is not necessary to answer the second question.”
學(xué)生：“第二題不需回答。”