Although the Carbon 14 method of dating old objects is not foolproof , it is the best method available at present
A、whollyoperationalC
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Peoplewhodonotsleepenoughtendtobecomeirritable.
Alllivingorganisms,regardlessoftheiruniqueidentity,havecertainbiological,chemical,andphysicalcharacteristicsincommon.
Thewheelsofthefirstroadvehicleswerefashionedfromcrudestonedisks.
TheNativeAmericaninterpreterSacajaweawasavaluablememberoftheLewisanddarkexpeditionin1805.
Someseaurchins海胆havevenomous(toxin)spines
