Language points
书本   百思  笔记本
   add      vt. & vi.   addition   n.     additional  adj.   add to    增加   add…to… 把……添加到……   add up  加起来；前后一致；合乎情理   add up to  总计，累计，总计达
Travel adds to your understanding of the world.Don’t add fuel to the flames.His story just doesn’t add up. He must be lying.His whole schooling added up to no more than one year.