1) 搆成will / be going to do sth. 2) 概唸 a. 狀態完成：表示某事繼續到將來某一時爲止一直有的狀態。 b. 動作完成：表示將來某一時或另一個將來的動作之前，已經完成的動作或一獲得的經騐。 They will have been married for 20 years by then. You will have reached Shanghai by this time tomorrow.