可持续性不再是可选项,而是任何想在21世纪蓬勃发展的企业的必需品。
对任何模型的最大期望是它能提供一个对现实有用的近似。
Concerning the gods, I cannot know either that they exist or that they do not exist, nor what form they might have, for there is much to prevent one's knowing: the obscurity of the subject and the shortness of man's life.