In________, he began to learn Russian, when he was in________.[ ]

A. 1970; the 50's  

B. the 1970; his 50s

C. the 1970s; his fifties  

D. 1970s; his fifties

能够直观反映与供应商之间往来款项账期情况的统计报表是（）

A.供应商期间对账单

B.应付账龄分析

C.往来资金预测表

D.付款单统计表