Making a difference（The Fifth Period）

     (show the screen.)
1. we often hear her sing the folk song.= she is often heard to sing the folk song.
2. the girl wanted to go dancing, but her mother told her not to
t: in the second sentence, “not” is put before the infinitive. (bb: not to do sth. ) to avoid repetition, the verb after the sign "to" is often omitted. but “to” can't be left out. this is done after such verbs as,, want, wish, like, love, hope, plan, try, hate etc. now look at the examples on the screen.
(show the screen.)
1.－would you like to come to a party?
 －i’d love to.
2.－have you listened
－no, but i plan to.
3. you don't have to eat it if you don't want to.
t: when the infinitive phrase is used as subject, the formal subject “it” is often used, that is, “it's+n./adj. + infinitive”. if we need to tell who performs the action of the infinitive, we can put "for sb./for sb. " before the infinitive. (bb: it's + adj. / n. + for/of sb. + infinitive.)some adjectives, such as, kind, good, wise, stupid, foolish, careless, clever…, must be followed by “of sb. to do sth. ” in this case, the sentence emphasizes “per- son”. if we use “for sb. to do sth.” it emphasizes “thing”. please look at the sentences on the screen and compare them, then fill in the blanks with “of” or “for”.
(show the exercise on the screen.)
1. it is silly        us to believe her.
2. it is impossible the task so soon.
3. it is nice        you to help me.
4. it is necessary        us to take exercise.
(teacher asks four answers.)
suggested answers:
1. of   2. for   3. of   4.for
t:  now look at the sentences on the screen. pay attention to the forms of the infinitive in the sentences.
1. she asked to be sent to work in tibet.
2. i am glad to have seen your mother,
3. we didn't expect you to be waiting for us here.
t: in the first sentence, the passive infinitive is used, which expresses a passive action. in the second sentence, we use the perfect infinitive. when do you think the perfect infinitive is used?
ss: when the action expressed by the infinitive happens before the predicate, the perfect infinitive should be used.
t: quite right. now look at the third sentence. the continuous form of the infinitive is used. when the action is happening, we use the continuous form of the infinitive.
 (bb: to be done, to have done, to be doing)
t:  now let's do an exercise.