我国对生态文明建设经历了一个从萌芽认识到视之为社会价值目标的认知过程。新中国成立初，受物质匮乏等历史条件的影响，处理人与自然的关系时强调征服自然；改革开放前，经济发展和生态环境的矛盾不突出，生态文明建设处于起步阶段。近年来，经济社会快速发展，生态建设遇到严峻的挑战，面对日益严峻的生态环保形势，党的十八大把生态文明建设放在突出地位，努力建设美丽中国。

结合材料，运用“认识的反复性和无限性”的知识，分析我国生态文明建设经历一个从萌芽认识到视之为社会价值目标的认知过程的原因。

阅读下面材料，在空白处填入适当的内容（1个单词）或括号中单词的正确形式。

    Today so many people are talking about AIDS, for which, ____ (fortunate)，there is no cure now. When we talk about its influence on our society, this disease is ____ most severe public health problem of all that we are facing in the 21^st century. It is spreading at a(n) ____ (surprise) speed, especially in Africa.

    The UN AIDS organizations have come to the ____ (conclude) that in the past 20 years, 20 million people have died of AIDS. And this figure will be three times bigger in the next two decades ____ measures are taken in poor countries. Only if people change their basic behavior in time, can AIDS ____ (stop) from spreading. For example, in San Francisco, the rate fell greatly when a serious program was carried out. People were ____ (please) to change their behavior when they realized how serious a risk they were taking.

    Experts think in order to get the message across to those ____ don't realize the seriousness of AIDS, a well ____ (design) educational campaign is the only thing at the moment that can help. It would be criminal not to put it into practice. So everyone has a share of responsibility in the fight ____AIDS.

斯塔夫里阿诺斯《全球通史》载：“远东是世界最后受到欧洲扩张影响的地区……由于推行强硬的闭关自守的政策，这里也没有潜在第五纵队(注：内奸)。”以下理解最为准确的一项是(　　)