---Where were you when I called at your house this morning?

---Oh, I_____ for a friend from Tokyo at the airport．

A．had waited

B．am waiting

C．have waited

D．was waiting

流通中需要的货币量取决于多种因素，其中不包括：

A．待售商品的数量

B．商品的价格水平

C．居民货币持有量

D．货币的流通速度