11.17 将来完成时
 
 1) 构成will / be going to do sth.
 2) 概念 
  a. 状态完成:表示某事继续到将来某一时为止一直有的状态。
  b. 动作完成:表示将来某一时或另一个将来的动作之前,已经完成的动作或一获得的经验。
   They will have been married for 20 years by then.
   You will have reached Shanghai by this time tomorrow.