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《Using LanguageⅠ》PPT课件优质课下载
the dates given to the bones that are
found. If the dates are wrong, all the
data about early people may also be
wrong. So Zhou Heping is very interested
to find out how archaeologists make
sure that their dates are accurate.
Listening and discussing
yogurt pots
orange skin
wastepaper
used envelopes
The waste paper basket
1 Listen to Part 1 of the tape and try to
understand “the wastepaper basket”
diagram on the right and fill in the layers.
It uses radioactivity to measure the amount
of _______ in living things. The _______ in a
dead body __________ at a ______ rate. We
know how long that takes, so we can measure
the amount of _______ and _________ how old
a bone is.
carbon
carbon
disappears
fixed