It was difficult for him to buy

It was difficult for him to buy good shoes because he had such a big__________of feet.
A、pair
B、size
C、couple
D、number
【正确答案】：A
【题目解析】：一双脚应说成a pair of feet。pair指大小，尺寸，重量，规格相等的两件东西，构成一副，一对，一双，一条等，而couple虽然也指一副，但并不指大小、尺寸等完全相同。couple指有关系的两个人或两件事。