亲：trousers作为复数来看,所以与它有关的只能是复数了.代词用they或者ones,动词用are,或者were.例如：A pair of teenage boys were smoking cigarettes.两个青少年正在抽烟.A pair of things are two things of the...就是说不是看pair，而是只看trousers么？那which　trousers　do　you　like？回答的答案也是ones，　they　have，　how　much　are　they吗？还是说提问一定要加pair　of，不能直接问which　trousers？是的，单位是pair。