当面对新资料或难度较大的资料时，几乎所有的听众都会面临挑战，因为人类口语缺乏书面文字的稳定性和永久性。
When new or difficult material is presented, almost all listeners are faced with a challenge because human speech lacks the stability and permanence of the printed word.
但在美国国家气候资料中心和其他公用数据库中，还是缺乏大量的气候数据。
But there is a lot of climate data the NCDC and other public databases don't have.
因为缺少设备，缺乏经验和技术资料，他们遇到不少困难。
They met with many difficulties, for they lacked equipment, experience and technical data.
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