It is difficult to get books back from people to whom you have lent them.把书借给别人后,要想要回

你不理解这句话 是因为你的断句不对. 这句话正确的断句应该是It is difficult to get books back from people to whom you have lent them. 前半句翻译“把书从人那里要回来是很难的”而...whom 指people . 而them 指books. 意思应该是：“谁让你借书”给人。　是这个意思吧！不是的 是借给“people”因为是to whom 这个地方是一个宾语前置这句中没有“谁”whom是代替 people的