(3) 在情景中确认某人或事物（不知性别的人） Who is it? It’s me. (敲门) ---Who’s it over there? ---It’s the milkman.
(4) 指代前句或后句所述的情况/事情 He smokes in bed and I don’t like it. It would be great if you could join us.
碰巧我当时没有带钱。 __It_h_a_p_p_e_n_e_d__th_a_t_I_d_i_d_n_’t_h_a_v_e_m__o_n_ey on me.
据说他已经入党了。 _I_t_is__s_a_id__th_a_t_h_e__h_a_s_jo_i_n_e_d_t_h_e_p_a_r_ty_._
一、代词 人称代词it可以用来代替一个名词、短语、句子， 以免重复。 (1)指代刚提到过的同一事物 （同类；同一） This is my new car. I bought it yesterday.
(2) 指动物或不考虑性别的婴儿 Where is the cat? It’s under the bed. The baby cried when it was hungry.
2) it, this 和 that
都可以替代前文已提到的事或情况，细微差别在于it不如其余 两者那么强调。
So she decided to paint the door pink. It upset the neighbours a bit.
So she decided to paint the house pink. That really upset the neighbours, as you can imagine.
(2) it用作形式宾语: 当__不_定__式___、_动_名__词____、_从__句____等用作宾 语且其后跟有 宾__补___时，使用形式宾语it，而将 真正的宾语移至句末。这类的动词有使役动词， find, make，feel, think, consider, see to it that…(务必)等。 如：
The computers in our school are connected to the Internet while those in their school aren’t. The football players on our team seem to be more energetic than those on your team.
I don’t like it when people talk with their mouths full.
I appreciate it if you can help me. 他讨厌别人用他的自行车。 _H_e__d_is_l_ik_e_s_/_h_a_te_s__it_t_h_a_t_p_e_o_p_l_e_u_s_e__h_is__b_ike 我不喜欢你生气的样子。 __I_d_o_n_’_t _li_k_e_it__w_h_e_n_y_o_u__a_r_e_a_n_g_r_y_. ________
A. It后用is/was这种单数形式。
B. 被强调部分是指人时，用_t_h_a_t_/_w_h_o__，被强 调部分指物时，用_t_h_a_t __。
C. 被强调部分是指时间或地点时，用that，一般
不用_w_h_e_n__，_w__h_e_r_e__之类的。
It is I who am right. 是我对。
当前面提到的事物不止一件时， it通常指最先提到的事物，而 This/that是指最后提到的事物。
We keep the ice cream machine in the spare room. It is mainly used by the children. (指 the machine) We keep the ice cream machine in the spare room. This/ That is mainly used by the children. (指the spare room)
A. it B. that C. these D. them
1）It’s (about / high) time + that-从句.(虚拟) 2）It’s first (second) time + that-从句. “某人第 几次做某事”。(从句用完成时) 3）It’s/has been + 时间段 + since-从句. “自从…
I find it easy to get on with her. I think it best that you should stay here.
(3)句式 A.喜好： enjoy, like, dislike, love, hate, appreciate it
when/ iபைடு நூலகம்/that….
That/ those一般用于替换有定冠词的名词； one/ones用于替换有不定冠词的名词。
The style of the building is similar to that of a temple. A CD player made in Japan costs more than one made in Hong Kong.
多亏有你我才仍然活着。
8)I took it for granted that he would help us. 我认为他会帮助我们的。 “认为…理所当然”
9)I depend on it that he will go with us. 我还指望着他能和我们一起去呢。
(4) 强调句 It is/was …that/who… 注意以下几 点：
他是死于日本。_It_w_a_s__in__J_a_p_a_n_t_h_a_t _h_e_d_i_ed___ 他是昨天结婚的。It_w_a_s__y_e_s_te_r_d_a_y_t_h_a_t _h_e_g_o_t_m__a_rr_ie_d__ 她是住在什么地方?_W__h_e_r_e_is__it_t_h_a_t _s_h_e_l_iv_e_s_?_______ 是谁教你们英语? _W_h_o__is__it_t_h_a_t_te_a_c_h_e_s__y_o_u_E_n_g_l_is_h_?_ 他是什么时候来的？W__h_e_n_w__a_s_it_t_h_a_t_h_e_c_a_m__e_?______
It’s a pity to refuse. 拒绝是令人遗憾的。 It’s no use saying any more about it. 再谈这事没有用。 It’s not known where she went. 她到哪里去了没人知道。
注：
A.It’s no use/ no good/ no pleasure/ useless/ a waste of…+doing B. It is said (reported / believed / expected/ accepted…) that… 据（报道，认为…）…. C.It happens (appears, seems…)that…; It struck me/occurred to me that…突然想到.. D. It is a pity(no wonder, ) that… E. It doesn’t matter that… …没关系 ; It makes no difference that… …没影响 F: It’s important(necessary, easy, kind…)
A．that B．this C．one D．it
2. Tom's mother kept telling him that he should work harder, ___ didn't help.
A.he B. that C. she D. but it
二、引导词it
一 it用作形式主语
(1) it用作形式主语:当_不_定__式___,_动__名_词___,_从__句__ 作主语时，常用it做形式主语，
B. 固定句式： 我们花费10天去那里。 It took __u_s_1_0_d__ay_s__to__g_o_t_h_e_r_e_____________ 轮到你来回答问题了。 It’s__y_o_u_r__turn__t_o_a_n_s_w_e_r_t_h_e_q__u_es_t_io_n________ 该吃饭了。It’s time to have dinner
That/ those一般不带前置定语，但必须有后置定语。 One/ones都可。 当替换词的后置定语用所有格的of短语或当替换词被 所有格修饰时，不用one/ones而用that of/those of.
I like the vase better than the one / that in another shop. The windows of your flat are cleaner than those of mine. A grandparent’s job is easier than that of a parent.
2. ___ one day they will have enough animals to set them free.
A. It is hoped for B. what is hoped that C. As is hoped that D. It is hoped that
it用作形式宾语:
有一段时间了”。 4）It’s + 时间段 + before-从句---“过多长时间才…” 5）It is up to sb to do sth. “该由某人做某事” 6)If it were not for…/ If it hadn’t been for… “若