主要的义务规则是那些要求或禁止某些行为的规则。

"When I write, I aim in my mind not toward New York but toward a vague spot a little to the east of Kansas."

创新不仅仅是创造新产品，更是重新构想我们如何解决问题。

诗人的任务是让沉默发声。

Sustainability isn't an option—it's a necessity for the future of agriculture.