It 句型归纳
    1. It is +adj.(+for sb./sth.) + to do sth.
    用于此句型的形容词有:easy, hard, difficult,possible, important, impossible, necessary, good, bad, exciting, interesting, surprising等。如:
    It is necessary to change your job.
    It was very hard for them to walk such a long way in the snow.
    2. It is +n.(+for sb./sth.) + to do sth.
    用于此句型的名词有: pity, shame, pleasure, one's duty, one's job, fun, joy, good manners, bad manners等。如:
    It is a pity for you to have missed such a wonderful play.
    It is bad manners for the young to take up the seats for the old.
    3. It is +adj.+of sb.+to do sth.
    此句型中的形容词主要描述某人的品德、特征。能用于该句型的形容词有:
    kind, nice, wise, silly, polite, impolite, friendly, foolish, clever等。如:
    How silly it was of you to give up such a good  chance!
    It is friendly of the family to try to make me feel at home in their house.
    4. It is +adj.(+n.)+doing sth.
    此句型中的形容词和名词常见的有:no/little use, no/much good, useless等。如:
    It's no use crying over spilt milk.
    5.It takes sb.+一段时间+to do sth. 表示"做某事花费某人多长时间"。如:
    It took us half an hour to ride to the town by the  sea.
    6.It is +及物动词的过去分词+that从句
    此句型中常见的及物动词的过去分词有:said, told, known, reported,
    recorded, thought, believed, considered等。如:
    It is reported that the Russian President will visit China next week.
    7.It +不及物动词+that从句
    此句型中不及物动词常见的有:seem, happen, appear, matter等。如:
    It seems that there will be a heavy snow tomorrow.
    It happened that I met my good friends in the museum yesterday.
    8.强调句型:It is+被强调部分+that/who从句
    在使用强调句型时要注意,指人时可以用who或that,其它情况一律用that。如:
    It was under the bed that my brother hid the ball this morning.
    It is Mr Bell who/that often comes and looks after the old man.
    9.It is/has been+一段时间+since从句。如:
    It is /has been three years since we saw each other last.
    10.It is (high) time that sb. did sth.
    该句型表示"某人现在该做某事了",从句常用过去时(虚拟语气)
    说明现在应该做的事情。如:
    It's six o'clock.It is high time that we went home  now.