it引导主语从句和it做形式主语还有强调句型的区别

it引导主语从句和it做形式主语还有强调句型的区别

“it”引导主语从句和“it”做形式主语还有强调句型的区别：
it引导的主语从句，形式主语就是it，真正的主语在句子的后面，通常是to do的不定式短语。
而强调句的结构 it is/was+被强调部分+that/who+句子其余部分，结构词it is/was和that/who都是没有实际意思的，只是构成句子结构的词而已。这个强调句只能强调名词和代词，也就是主语和宾语，不能强调其他句子成分。
主语从句：It is kind of you to help me with my housework.
强调句：It is you who help me with my housework.

主语从句中it做形式主语的常见句型：
It + be + 形容词+主语从句，如：It is uncertain whether he can come to Jenny’s birthday party or not.
It + be + 名词词组 + 主语从句，这类名词有：a fact, a pity, a shame, an honour，a question等，如：It’s a pity that you missed the exciting football match.
It remains a question whether he will come or not.
It + be + 过去分词+ 主语从句，这类过去分词有：announced, believed, expected, hoped, decided, reported, said, shown等，如：It is reported that 16 people were killed in the earthquake.

it引导的主语从句，形式主语就是it，真正的主语在句子的后面，通常是to do的不定式短语。
而强调句的结构 it is/was+被强调部分+that/who+句子其余部分，结构词it is/was和that/who都是没有实际意思的，只是构成句子结构的词而已。这个强调句只能强调名词和代词，也就是主语和宾语，不能强调其他句子成分。
你可以对比一下下面两句：
主语从句：It is kind of you to help me with my housework.
强调句：It is you who help me with my housework.

额，你所谓的it引导主语从句是说“it 作形式主语的主语从句吧”
那么“it作形式主语的主语从句”和“强调句”的一个最简单的判断方法是把句子的后半部分挪到前面来然后看句子里面有几个动词，有一个就是强调句，两个就是it作形式主语的主语从句
举个例子：
1. It is English that he teaches us.
把后面挪过来为
He teaches us English.
有一个动词 teach，所以为强调句
2. It is interesting that he can teach us English.
那把后面挪过来为
He can teach us English is interesting.
有两个动词 can teach 和 is ，所以为主语从句
另外还有一个不同点是，强调句只能用that，主语从句还可以用别的
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it引导的主语从句，形式主语就是it，真正的主语在句子的后面，通常是to do的不定式短语。
而强调句的结构 it is/was+被强调部分+that/who+句子其余部分，结构词it is/was和that/who都是没有实际意思的，只是构成句子结构的词而已。这个强调句只能强调名词和代词，也就是主语和宾语，不能强调其他句子成分。
你可以对比一下下面两句：
主语从句：It is kind of you to help me with my housework.
强调句：It is you who help me with my housework.
主语从句中it做形式主语的常见句型
常见句型有：
1. It + be + 形容词+主语从句，如：
It is uncertain whether he can come to Jenny’s birthday party or not.
2. It + be + 名词词组 + 主语从句，这类名词有：a fact, a pity, a shame, an honour，a question等，
如：It’s a pity that you missed the exciting football match.
It remains a question whether he will come or not.
3. It + be + 过去分词+ 主语从句，这类过去分词有：announced, believed, expected, hoped, decided, reported, said, shown等，
如：
It is reported that 16 people were killed in the earthquake.
It is not decided who will give the operation to the patient.
it做形式主语 必须用that引导从句吗
不是必须..
it做形式主语，后面内容做句子真正主语，除了由主语从句充当之外，还可以由不定时，不定时短语，动名词以及动名词短语充当，
例如下面句子
It is very useful to learn English so well
It is the police's duty to protect the peope's life and properties
It is not so effective learning English without practising speaking English with others as often as possible
It is his duty taking good care of all his children.