A: You look very nice in your new dress today.B: Oh really? I it when it was on sale.A.

问题补充：

A: You look very nice in your new dress today.

B: Oh, really? I it when it was on sale.

A. buy

B. bought

C. have bought

D. will buy

答案：

A. buy

(答案→)B. bought

C. have bought

D. will buy

解析：句意：今天你穿这件连衣裙看起来很不错。——哦，真的吗？我是在它减价处理的时候买的。结合语境可知下文描述的是过去某时进行的动作，故用一般过去时态，选B。