1) 構(gòu)成will / be going to do sth.
2) 概念
a. 狀態(tài)完成：表示某事繼續(xù)到將來某一時(shí)為止一直有的狀態(tài)。
b. 動作完成：表示將來某一時(shí)或另一個(gè)將來的動作之前，已經(jīng)完成的動作或一獲得的經(jīng)驗(yàn)。
They will have been married for 20 years by then.
You will have reached Shanghai by this time tomorrow.
