For investors who desire low risk and guaranteed income,U.S. Government bonds are a secure investment because these bonds have the financial backing and full faith and credit of the federal government.
出自-2014年6月阅读原文
Well, that's a good question, because the basic idea of chaos theory is that there aren't any "models" as such— there aren't guaranteed forms, but rather patterns of change in development
出自-2013年6月听力原文