1. Life on Earth will become unsustainable unless population growth is held in check. 地球上的生命将无法延续，除非人口增长得到控制。
2. It's not only unsustainable for workers, but also for the companies that employ them. 这不仅对工人是不可持续的，对雇佣他们的公司也是如此。
3. Peter Orszag, Obama's Budget Director, recently called the US budget deficits unsustainable and he's right. 奥巴马政府的预算主管彼得·奥斯泽格最近称，美国的预算赤字是不可持续的，他是对的。
4. Peter Orszag, Obama's Budget Director, recently called the U.S. budget deficits unsustainable—this year's is $1.4 trillion—and he's right. 奥巴马的预算主任彼得·奥斯泽格最近宣称美国的预算赤字是无法维持的——这一年是1.4万亿美元——他是对的。
