Howdidpeopletellthetimebeforeclockswereinvented?Atfi...
问题详情： Howdidpeopletellthetimebeforeclockswereinvented?Atfirst,theancientpeoplelookedupatthesunandcouldtellitwasthemiddleofthedaywhenthesunwasdirectlyoverheadinthesky.Theyalsoknewwhenitwasmorni...