作为确认暴利的利润标准，“四个同一”是指( )。

A．同一地区

B．同一时期

C．同一档次

D．同一价格

E．同种商品或服务

—How do you go to school every day?

—I ____ , but I ____ by bike a year ago.

A．go to school by foot; went

B．would go to school on foot; liked to go

C．walk; used to go

D．will walk to go school; was used to going