If these trouser are too short,buy a bigger( )

问题描述:

If these trouser are too short,buy a bigger( )
1 one
2 pair
3 ones
选出选项,并说明选择的理由

Pair
a pair of trousers 固定搭配
trousers不能用单数形容,所以不能选one
另外如果用ones的话,应该是buy another bigger ones