They became friends again that day. Until then, they _____ to each other for nearly two years. [ ]

A. didn't speak

B. hadn't spoken

C. haven' t spoken

D. haven' t been speaking

存款准备金政策是以商业银行的货币创造功能为基础的，其效果也是通过影响商业银行的货币创造能力来实现的。