他已经在北京呆了十周了:
he has been in beijing for ten years.
He said :"I bought this book two years ago"改为间接引语:
he told me that he bought this book two years ago一般过去时改为间接引语时时态要变成过去完成时吧，我不明白的是间接引语时是否是He said that he had had(还是bought) this book ten years before.o 对。he told me he had bought this book two years before