安全困境是国际政治的一个基本特征，因为国家增加自身安全的努力往往会降低其他国家的安全。
The security dilemma is a fundamental feature of international politics, as states' efforts to increase their own security often decrease the security of others.
Urban forestry proves that nature and cities can thrive together.
要解决问题，你必须愿意以不同的方式思考。
过度捕捞是对子孙后代的盗窃。