*_I_t _o_c_c_u_r_re_d__t_o_m__e_t_h_a_t_(我突然想起)I forget to sent the letter.
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4) It + be +过去分词+从句
It is said that...
据说……
It is known to all that... 众所周知……
It is a pity/shame that... 遗憾的是…… It is a surprise that…令人惊奇的是… It is a fact that… …是事实 It is common knowledge that… …是常识
*__It_i_s_a__p_i_ty__th_a_t__(很遗憾)we lost the match.
It makes no difference whether
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T or F questions
：They should like each other is natural. ：That they should like each other is
natural. ：It is natural that they should like
表语从句
The news that we won the game is exciting.
同位语从句
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Noun Clauses (名词性从句)
Subject Clause (主语从句)
Object Clause （宾语从句）
Predicative Clause （表语从句）
Appositive Clause （同位语从句）
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Complete the sentences using what, whether,
where, when， who, why, how or that.
1.(_W_h_a_t_ is needed for success) is your hard work. 2.( When/Howthey will arrive )has been told to the teacher. 3.( Where/whether we will go tomorrow )hasn’t been decided yet.
Subject Clause
引导主语从句在句首只能用whether, Conclusion: 有it作形式主语的whether/if都可以. 7
注意: 由that 引导的主语从句有时为了使句
子结构平衡, 避免 “头重脚轻”, 常用 it 作形式
主语, 而把从句放在后面。 例如:
1. That he will refuse this piece of advice is impossible. __I_t _is__im__p_o_s_s_i_b_le__th_a_t_h__e_w_i_ll_r_e_f_u_s_e_t_h_i_s_p_i_e_c_e __o_f_a_d_v_i_c_e_._____________________________
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If ×
Whether the solid shape would last or not wa.s not clear.
if It was not clear whether the solid shape
would last or not.
Real Subject
Formed Subject
each other. ：If Mary really heard him is really doubtful. ：It was doubtful if Mary really heard him.
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2.连接代词who ，what ，which, whatever, whichever, whoever What many scientists believe is that the continued presence of water …
It must be pointed out that…需指出的是……
*_I_t_i_s__re_p__o_r_te__d_t_h_a_t__(据报道)20 people were
killed in the accident.
*__It__is__s_u_g_g__e_s_t_e_d__th_a__t __(建议)we should eat
passengers_(s__h_o_u_l_d_)_b_e__s_e_a_r_c_h__e_d_.
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3) It +不及物动词+从句
It happened that...
碰巧……
It occurred to me that…我突然想起…
*_I_t_h_a_p_p_e_n_e_d__t_h_a_t_(刚好)I came into the office at that time.
7.(_T_h_a_t__ the earth is a solid ball) is known to us all. Conclusion: 主语从句作主语时，谓语动词一般用单数形式。
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Summary:
Subject Clause
1. 用 that / whether / if/ /where / how / when /why / who /what/which/ how much / etc. 来连接主语从句.
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4.(_W__h_o__ can join in the sport meet) is decided by the teacher.
5.(_W__h_e_th_e_r_ it will rain or not) is not clear. 6. (_W__h_y the earth is becoming warm) is a good topic for research.
*__It_i_s_a__f_a_c_t _th_a_t_(这是事实)he cheated in the exam.
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2) It is + adj. +从句 It’s certain that… 肯定… It is possible that... 很可能…… It is unlikely that... 不可能…… It is obvious that… 很明显… It is necessary \important \natural\... that… +(should) +do…
more vegetable and do more exercise. 14
• 5)“无关紧要（的是）”
It doesn’t matter
+主语从句
It makes no difference
• 翻译：一个人是否富有无关紧要
_It_d_o_e_s_n_’_t_m__a_tt_e_r_w_h__e_th_e_rone is wealthy or not.
It is strange that_h_e__s_h_o_u_l_d_n__o_t_c_o_m__e_.
我们做足够的运动很重要。 重要的是我们应该做足够的运动
It is important that we should do enough sports.
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• ②表示“据建议、据要求、据命令” • It+be+suggested/advised/ordered/requested/ commanded/ insisted/required that… 谓语形式:should + V.原形 , should可省略. • 据命令，所有乘客必须接受搜查 _I_t_w_a__s_o_r_d_e__re_d__t_h_a_t_all the
Who will take part in the meeting has not been decided.
Whoever breaks the law will be punished.
Which student will win the first is
uncertain.
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3)连接副词when，where， how， why等。
It is reported that... 据报道……
It is believed that...据信……;人们相信……
It is suggested that + (should）do... 建议……
It must be admitted that…必须承认……
It cannot be denied that… 不可否认……
*_I_t_i_s_p_o_s_s_i_b_le__th__a_t _(很可能)she will come back tomorrow. *__It_i_s_o__b_v_io_u_s__th__a_t _(很明显)this measure is
effective.
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※ 主语从句的虚拟语气
①表 “应该，惊讶、惋惜、遗憾”等意义 It is important /natural /necessary/impossible/strange that... 谓语形式为:should + V.原形 , should可省略。 eg. 很奇怪，他竟没有来。
*it为形式主语
2.That they should like each other is natural. _I_t _is__n_a_tu__ra_l_t_h_a_t_t_h_e_y_s_h_o_u__ld__li_k_e_e_a_c_h__o_th__er.
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这样就构成了下面一些常用句型: 1) It is + n. +从句
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名词性从句的作用相当于名词，因此主语从 句、表语从句 、宾语从句和同位语从句分别 作主句的主语、表语、宾语和同位语。