[] () an investment in the form of an agreement to lend a sum of money for ten years or more to a company or government who will pay it back with interest（十年以上还本付息的）长期债券，长期公债◆Long bonds are affected more by interest rate changes than short-term bonds.长期债券比短期债券更易受利率变动的影响。a thirty-year bond issued by the US Treasury美国财政部发行的三十年期的国库券