帮变一下被动语态
1.ThomasEdisoninventedthelightbulb.
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2.DrBellinventedthetelephone.______________________________
3.PeopleinventedpapermakinginEasternHanDynasty.
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4.ShenNongdiscoveredthisbeverageoverthreethousandyearsbeforethat.
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5.Peopleusestampsforsendingletters.