Manyobjectsthatareusedinoureverydaylifestartedwithasimpleidea.theseobjectshaveoften(
thewaywelive.someofthemhelpustodoajobmoreeasily,andothershelpustofillaneed.In1858,Lhadsuchanidea.Hetook()apencilapieceofpaperandaneraser,hebegantowrite.Buthehadchangeaword.Eachitimehehadtosearchhisbooksandpaperstofindtheeraser,hefeilit().Lthoughthardandthenhehadhis()idea.hecutagrooveinone()ofthepencilandgluedtheeraserintothisgroove.hefind()moreconvenientforhimtousehiseraser.hedidn'tneedto()forhiseraseragain.括号里填一个单词.