It is difficult for us to learn a lesson in life _____we’ve actually had that lesson.

A．until

B．after

C．since

D．when

我国政策性的营运资金，除财政拨付的资本金之外，主要来源于( )。

A．发行有价证券

B．邮政储蓄

C．向社会发行金融债券筹集资金

D．居民存款