今后20年是我国地理科学跨世纪发展的奠基期和开拓期。
The coming 20 years is a founding and opening period of geography's trans - century development.
从20世纪60年代至今，世界GIS的发展经历了四个阶段：开拓期、巩固发展期、大发展期和现在的用户时代。
From the 60's of 20th century up to now, the development of the world GIS experienced four stages: Expanding period consolidating period, development period and the consumers' period.
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