国债定向发售方式
参考答案：
向养老保险基金、失业保险基金、金融机构等特定机构发行国债的方式，主要用于国家重点建设债券、财政债券、特种国债等品种。
We went through a period _____ communications were very difficult in the rural areas. [ ]
A. which
B. whose
C. in which
D. with which
下引线采用圆钢直径不应小于( )mm。(烟囱除外)
A．8
B．10
C．12
D．16
