3．Do you know that humans have been cleaning their teeth for over 7，000 years？According to the BBC，the Ancient Egyptiansused a type of toothpaste （牙膏）．（21）Cit is believed that the Egyptians used afinger （22）Aa toothbrush to clean their teeth．Chinese people may have （23）Dthefirst toothbrush around 1，600 BC．
Your toothbrush，however，may have also become（24）B．Because it is now possible toclean our teeth （25）Cusing our hands!
Two Canadians，Adel Elseri and Said Fayad，have invented（26）Dcalled T2T or"tongue-to-teeth"Elseri says he came up with the idea（27）Bhe was driving home after a long day at work．His（28）Ais a toothbrush that goes onto your tongue（舌） T2T has special edges （邊緣） and toothpaste．So just （29）Cyour tongue over your teeth and it cleans your teeth just like a toothbrush（30）B!It will make your breath fresh too
Elseri and Fayad made this hand-free toothbrush because theybelieved it was a （31）Bway for someone to brush their teeth．But people can only use the T2T （32）C．
Would you use the tongue-to-teeth？The Huffington Post in the US（33）Breaders what they thought．Sixty-one percent said that they would use it while only thirty-nine percent said they （34）C．Personally I think I'm going to stick to（堅持用） the （35）B．
| 21．A．So | B．Then | C．But | D．Or |
| 22．A．instead of | B．becauseof | C．more than | D．less than |
| 23 A．discovered | B．develop | C．built | D．developed |
| 24 A．science | B．history | C．problem | D secret |
| 25．A by | B．from | C．without | D for |
| 26．A．nothing | B．everything | C．anything | D．something |
| 27．A．until | B．when | C．since | D．though |
| 28．A．idea | B．story | C．word | D．plan |
| 29 A．hold | B．pull | C．move | D．check |
| 30 A is | B．does | C．was | D．did |
| 31 A healthier | B．easier | C．harder | D．longer |
| 32 A．again | B．soon | C．once | D already |
| 33．A．told | B．asked | C．warned | D．advised |
| 34．A．shouldn't | B．should | C．wouldn't | D．would |
| 35．A finger | B．toothbrush | C．mouth | D tongue． |
