1. In this area , the ecological environment is very rigorous for living things, and aridness and wind and arid are main threats. ���������ɳĮ��������Į��������̬����ʮ���Ͽᣬ�ɺ��ͷ�ɳΪ��������Ҫ����̬�������⡣
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n.
1. a deficiency of moisture (especially when resulting from a permanent absence of rainfall)