1、 Vanity is a constant; people will only start shopping more sustainably when they can't afford not to.
虚荣心是永恒的；人们只有在不能承受放纵购物的时候，才会开始节制购物。
来源:
2、 To supporters, GM crops are a key part of the effort to sustainably provide food to meet a growing global population.
为满足日益增长的全球人口需求，需要付出努力，持续地提供粮食。对于支持者来说，转基因作物是这一努力的一个关键部分。
来源:
文