20×20Unit9Whenwasitinvented?LanguageGoal:Talkaboutthehistoryofinventions.Grammar:被动语态（ThePassiveVoice）重点归纳话题Inventions发明功能项目Talkaboutthehistoryofinventions谈论发明物的历史重点短语1.wasinvented被发明2.beusdfor被用来做…3.beinventedby+sb.被某人发明4.inthedark在黑暗中5.Themosthelpfulinvention最有用的的发明6.everyday每天7.bymistake错误地8.thin(salty)enough足够薄（咸）9．Makesb.Happy使某人高兴10．Intheend最后11．Itsaythat…据说12．Foralongtime好长时间13．Byaccident偶然14．Wasdiscovered被发明（发现）15．Accordingto根据；…16.Fallinto掉进…落入17．Decidetodosth.决定去做某事18．Inthisway这样19．Prefer…to…比起…更喜欢…20.travelaround环游21．Knockinto与…想撞22．Divide…into把…分成23．Takepartin参加24．Thenumberof…的数量25．Dreanof梦想26．Merethan多于，lessthan少于重点句型1．Whenwasitinvented?2．Whoweretheyinventedby?3．Whataretheyusedfor?语法要点1．一般过去式的被动语态was/were+done