钠米铜具有超塑延展性，在室温下可将它拉长达（）多倍而不出现裂纹。
A.50；
B.500；
C.100；
D.1000。
参考答案：A
我国21世纪以来，金融管理制度创新的内容可表述为( )。
A．黄金市场开锣
B．对于混业经营的尝试
C．设立同业拆借市场
D．设立证券市场
Which of the following choices correctly places callable bonds, straight coupon bonds, mortgage-backed securities, and zero-coupon bonds in order from the type of security with the least reinvestment risk to the one with the most reinvestment risk（）
A. zero-coupon bonds, mortgage-backed securities, straight coupon bonds, callable bonds.
B. zero-coupon bonds, straight coupon bonds, callable bonds, mortgage-backed securities.
C. mortgage-backed securities, zero-coupon bonds, callable bonds, straight coupon bonds.
