一、在英文中，名詞或名詞短語主要充當(dāng)四種成分，主語、賓語、表語和同位語。
    如果我們把句子當(dāng)作名詞來使用，分別在另一個(gè)句子中作主語、賓語、表語和同位語(見下表第二列)，于是就構(gòu)成了四種從句：主語從句、賓語從句、表語從句和同位語從句。因?yàn)橐詾檫@四種從句在本質(zhì)上相當(dāng)于名詞的作用，所以我們把他們統(tǒng)稱為名詞從句。請(qǐng)看例句：
    二、三種句子來充當(dāng)四種成分。
    上面說到名詞從句就是用一個(gè)完整句子充當(dāng)另一個(gè)句子的某種句子成分便構(gòu)成了具體某一名詞從句。那么可以用什么樣的句子來充當(dāng)四種成分呢？答案是：
    三、陳述句可分別充當(dāng)四種句子成分(名詞從句的重點(diǎn)內(nèi)容)，要在陳述句首加上他that。
    對(duì)于陳述句，我們要在句首加上that,然后把“that+陳述句”分別放在另一個(gè)句子的四種位置即構(gòu)成四種名詞從句。
    1.主語從句?！皌hat+陳述句”在主語位置即成主語從句：
    Stuart is ugly.
    That Stuart is ugly is a fact..
    That Malaysians don’t speak good English is obvious.
    更常見的是用it式主語置于句首，而將主語從句放在句末。例如：
    It is a fact that Stuart is ugly.
    It is obvious that Malaysians don’t speak good English。
    因此下面都是常見的主語從句句型：(￥)
    ①It is +過去分詞 +that 從句(found, believed, reported, thought, noted…)
    ②It is +形容詞 +that 從句(clear, possible, likely, natural, certain, fortunate, necessary, strange…)
    ③It is +名詞(短語) +that 從句(a pity, a shame, an honor, a good idea, a miracle…)
    2. 賓語從句。“that+陳述句”在賓語位置即成賓語從句：
    I think (that) you turned off the light.
    We know (that) women love shopping.
    She believed (that) her child was premature.
    只有賓語從句中的that才可以省去，其他名從that不省。
    3.表語從句?！皌hat+陳述句”在表語位置即成表語從句：
    My idea is that the students should be more open to each other.
    The reason is that he was careless and irresponsible.(考點(diǎn))
    4.同位語從句。“that+陳述句”在同位語位置即成同位語從句：
    所謂同位語，就是用來補(bǔ)充說明名詞的成分。
    The rumor that Tom washed his socks once a month turned out to be untrue.
    Our fathers brought forth upon this continent a new nation, conceived in liberty and dedicated to the proposition that all men are created equal.
    A saying goes that tomorrow is another day.