Nobodyknowswhoinvent的精选

问题详情：Nobodyknowswhoinventedthepencilorwhenitwasinvented.ASwiss(瑞士人)describedapencilinabookin1565.Hesaiditwasapieceofwoodwithlead(铅)insideilsweren’tpopularatthattime,andpeoplecontinuedtowritewi...