Until recently historians assumed that calendars came into being with the advent of agriculturE.No one supposed that man was making a real effort to understand the seasons 20,000 years_____. A.ago B.before C.since D.back
A.No B. A.ago C.before D.since E.back
【参考答案】
B 本题考查考生综合分析能力。考的是人类真正了解季节变化的时间。文章最后一句(Itseemsthatmanwas......