刚做的一篇综合写作，大家帮忙看看

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The lecture is mainly discussing the reasons why the Anasazi people lived in Chaco Canyon disappeared suddenly, challenging what are stated in the reading passage that Anasazi's people were vanished by global warming.
   First of all, the speaker thinks there may be a global warming happened at that time, but it affected other places instead. the reason to support the speaker is that many trees still exist for thousands of years, if the place really experienced a severe summer droght, these trees have already died. In contrast, the reading passage believes that the global worming caused severe summer drought at Canyon, which led the Anasazi could not cope with and were forced to abandon their home. So the lecture disagrees with the view in reading.
   Second, the speaker discusses the parpose on building irrigation system is not necessary to means the Anasazi suffered a severe drought, because the system existed more than 150 years which means that the people there are fully-aware of the problems they faced, and they had highly technology to against the drought.
    Finally, the speaker raises the issue that the summer drought is just a hypothesis, and the global warming is not severe enough to let Anasazi people to abandon their village. Instead, the Anasazi might be attacked by other tribes, severe disease or overuse of landfarm, yet just simply because of severe drought.