新概念英语第三册 Lesson 38(课文6)

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7.Up to now, historians have assumed that calendars came into being with the advent of agriculture,for then man was faced with a real need to understand something about the seasons.
   up to now = so far 到目前为止
come into being == come into existence 产生，出现
  be faced with a real need to do sth. 面临着做某事的真正需要
Ex
We are faced with a real need to learn English well.
8. Recent scientific evidence seems to indicate that this assumption is incorrect.
   indicate 揭示
9.By correlating markings made in various parts of the world, historians have been able to read this difficult code.
   correlate  相互联系
  By...world作方式状语,修饰 have been able to read . 此介词短语中的made in...world 为过去分词短语作定语,修饰markings.
10. It has long been known that the hunting scenes depicted on walls were not simply a form of artistic expression.
   It作形式主语,其后由关系连词引导的从句为逻辑主语. that 从句中的depicted on walls 为过去分词短语, 作定语, 修饰scenes.