从今天开始我们要专攻助动词。好啦，现在大家先来回忆一下助动词有哪一些？
助动词包括：be (is, am, are, was, were, been, being)；have (has, had, having)；do (does, did)；shall (should), will (would)
" be + 动词不定式"可以表示下面几种意思:
1.命令或指示。例如：
No one is to enter the room without permission.
2.计划或安排。例如：
A new bridge is to be built over the river soon.
3.可能。例如：
This kind of tree is to be found in that forest.
4.应该。例如：
Such people are to be criticized.
5.表示后来发生的事，可以用来表示一种命运。例如：
They said good-bye, little knowing that they were never to meet again.
Task:这一期你的任务一:仔细观察下面三个句子,指出各个句子中的＂be+动词不定式＂是上面五种意义的那一种。
1.The books are not to be taken out of the reading-room.
2.The expedition is to start in a week’s time.
3.He was to regret the decision.