He worried about its future. Roosevelt wrote: "I recognize the right and duty of this generation to develop and use the natural riches of our land.

VOA: special.2010.08.12

As readers, it's our duty, it's our obligation, to sort out and to reassemble.

作为读者，我们的任务和责任，就是鉴别挑选和重组。

耶鲁公开课 - 弥尔顿课程节选

For Comus, nature has given us all of her riches and it's our duty, it's our obligation, to spend them, to consume them, and to luxuriate in nature's generosity.

科玛斯认为，自然赋予我们她所有的财富，我们有职责有义务去使用消费它们，自然如此慷慨大方，我们有义务去享用。

耶鲁公开课 - 弥尔顿课程节选

s our duty as Americans to put you on the right track."

作为美国人我们有义务，And，it’,让你回归正道“

普林斯顿公开课 - 国际座谈会课程节选