If these trousers are too big buy a smaller＿＿＿A. set B. one C. copyD. pair

问题补充：

If these trousers are too big, buy a smaller＿＿＿．

A. set

B. one

C. copy

D. pair

答案：

A. set

B. one

C. copy

(答案→)D. pair

解析：trousers, scissors, gloves, socks, glasses等表示成双成对物品的名词，其数量单位为 pair。