i want to buy a pair of trousers.这里want后面为什么用动词原型

I want to buy a pair of new trousers to ___ my sweater. A．go I want to buy( ).A a trousers B a pair trousers C a trousers I want to buy a pair of trousers.Hou much () they I have worn out my shoes ,I want to buy a new pair. 为什么用pair i want to buy a pair of shoes I want to buy a pair of shoes=? I want to buy a pair of shoe.咋改? I want to buy a pair of gloves I want to buy a pair of shoes.速度中文 i want to buy a pair of l_ shoes i want to buy _____tomorrow.A a pair of shoes B a pair of sh i have two pairs of shoes and i want to buy a () pair 用 thre