高二英語(yǔ)usinglanguagelistening-資料下載頁(yè)
2024-11-09 03:45本頁(yè)面
【導(dǎo)讀】the“wastepaperbasket”diagrambelow.arewhenyoufindthem?dating.texture.ZH:Howdoesthathelp?manylayersarethere?ZH:Now,letmethink!Yes,it'llbethe. envelopes.RL:Andwhere'stheoldestlayer?ZH:Atthebottom.sameageasthesoil.ZH:Isee.method.strangename.plantis.accuratetoo?10,100yearsold.ZH:Howclever!Howoldarethebones. 40,000yearsold.togethersometime?
【正文】 in a dead body disappears at a fixed rate. We know how long this takes, so we can measure the amount of carbon and work out how old a bone or plant is. ZH: That39。s very clever. Is it very accurate too? RL: There are some problems, so you are always given a date plus or minus some years. For example, your bone may be dated to 10,000 years ago plus or minus 100 years. This means the bone is between 9,900 years and 10,100 years old. ZH: How clever! How old are the bones from the Zhoukoudian Caves? RL: They are between 250,000 and 40,000 years old. ZH: Perhaps we can go and visit the site together sometime? RL: Of course. Whenever you like!
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