Dad my trousers are old. I want to buy a new .A. trousers B. one C. it D. pair

问题补充：

Dad, my trousers are old. I want to buy a new .

A. trousers

B. one

C. it

D. pair

答案：

A. trousers

B. one

C. it

(答案→)D. pair

解析：

Trouser裤子在使用时用的复数，故不能直接用one或it来代替。表达一条裤子我们可以说a pair of trousers，故选D。