单选题 You may borrow this book ______ you promise to give it back.
  • A.as far as
  • B.as long as
  • C.so far as
  • D.as longer as
【正确答案】 B
【答案解析】[解析] as long as=so long as表示“只要，在…的时候”。as far as表示“远到，直到，至于”。