(1) 前者表示为将来做出的安排。
- The Queen is to visit Japan next year.
明年女王将访问日本。 - There's to be a rail strike on July 18th.
7月18日将有一场铁路罢工。
(2) 这种结构也可用于过去，表示过去某个时间为将来做出的安排，如果这安排未按计划发生，则用不定式的完成式。
- I felt nervous because I was soon to leave home for the first time.
我感到紧张是因为我很快就要初次离家了。 - I was to have started the work last week, but some other thing intervened.
我本来要在上周开始这项工作的，但中间又发生了别的事。
(3) 有时，这种结构不是表示计划中的安排，而是指“注定的(隐藏在将来的)事”。
- They said goodbye, not knowing that they were never to meet again.
他们道了别，并不知道他们将再也不会相聚了。
(4) be+to do sth.结构也可用来发出命令(如：父母常告诉孩子做什么事)。
- You're to do your homework before you watch TV.
你得做完家庭作业再看电视。 - Tell her she's not to be back late.
告诉她可不要回来晚了。
(5) 在发出通知、下达指示时，不定式常用被动式。
- The form is to be filled in and returned within three weeks.
本表要在三周内填好交回。 - These tablets are to be kept out of the reach of children.
这些药片要放在孩子们够不到的地方。
(6) 在这种不定式前，主语和助动词可以略去不用。
- To await arrival.
(写在信封上)等待抵达。 - To be taken three times a day before meals.
(写在药瓶上)饭前服用，一天三次。
(7) 注意see, find, congratulate不定式被动结构与be连用的特殊用法。
- He's nowhere to be seen .
哪里也见不到他。 - She's nowhere to be found .
哪里也找不到她。 - You're to be congratulated .
祝贺你！
