根據(jù)首字母提示完成短文（八上寒假作業(yè)）
When Mary Smith was a student,she always wanted to be a t___,because she liked children.When she was twenty-two y___ old,she began teaching in a small s___.She was a good teacher.The c___ liked to come to her class.One day,one of the girls in her class said to her,"Miss Smith,why does a m___ hair become white before his beard?"Mary laughed and a___,"I don`t know,but it h___ to my father!"The other children laughed when they h___ this.Then on of the boys said,"I know,Miss Smith.Men`s hair b___ white because it`s sixteen years o___ than their beard."