Please list the two basic uses of the past perfect. Give an example for each.
【正确答案】：Past perfect has two basic uses: finished use and unfinished use. E.g. He had lived here before I moved in. I had known him for quite a long time before you offered to introduce him.
【题目解析】：过去完成时的用法，完成的动作和未完成的动作。