很多学生看到it在句首就以为是”它”的意思。但在英语写作中，it有四种完全不同的功能——认错一个，整句话的意思就变了。
前两天批改一篇雅思作文时，学生写：
“It is important to learn English that everyone knows.”
他想表达”众所周知，学英语很重要”——但句子结构混乱了。正确的写法是：“It is well known that learning English is important.”
📊 厦门灯塔威廉老师批改数据： “it句型”是中国学生写作中的高频出错区域，约45%的学生在使用it句型时出现结构错误。最集中的问题是强调句（It is…that…）与形式主语句（It is…to do）的混淆——这两种结构看起来很像，但语法功能完全不同。
一、it句型三兄弟一览
| ”三兄弟” | 结构 | 功能 |
|---|---|---|
| 大哥：形式主语 | It is + adj + to do / that | 把长主语挪到后面 |
| 二哥：强调句 | It is + 被强调部分 + that/who | 突出某个成分 |
| 三弟：形式宾语 | S + V + it + adj + to do / that | 让宾语不臃肿 |
二、大哥：形式主语（It is…to do / that…）
核心逻辑： 英语不喜欢”头重脚轻”。如果主语是一个很长的to do或that从句，英语习惯用it代替它放在开头，把真正的主语挪到后面。
对比：
- ❌ To learn English well is important.（没错，但头重脚轻）
- ✅ It is important to learn English well.（更自然）
- ❌ That he passed the exam is surprising.（没错但不自然）
- ✅ It is surprising that he passed the exam.（更地道）
写作中常用模式：
| 结构 | 例子 |
|---|---|
| It is + adj + to do | It is necessary to protect the environment. |
| It is + adj + for sb + to do | It is important for students to exercise regularly. |
| It is + adj + that从句 | It is obvious that technology has changed our lives. |
| It is + 名词 + to do / that | It is a good idea to start early. |
| It takes + sb + time + to do | It takes me two hours to finish my homework. |
写作加分技巧： 与其写”Learning English is important”，不如写”It is essential for modern students to master English communication skills”——更正式、更适合学术写作。
三、二哥：强调句（It is…that/who…）
这是学生最容易和大哥混淆的句型。强调句的功能是突出句子中的某个成分——去掉”It is…that/who”后，剩下的仍然是一个完整的句子。
判断方法： 去掉”It is…that”，剩下的句子是否完整？
- ✅ 强调句： It was Tom that/who broke the window. 去掉→ Tom broke the window.（完整✅）
- ❌ 不是强调句： It is important that we study hard. 去掉→ Important we study hard.（不完整❌——这是形式主语）
强调句的三种常见形式：
| 被强调部分 | 例子 |
|---|---|
| 强调人（主语） | It was my mother who taught me to read. |
| 强调物（宾语） | It is this book that I want to recommend. |
| 强调时间/地点 | It was in 2020 that the pandemic started. |
| 强调原因/方式 | It is because of hard work that he succeeded. |
写作中的妙用： 在议论文中，用强调句来突出你的核心观点，让读者知道”这是我想强调的重点”。
It is not the lack of ability that holds students back, but the lack of proper guidance.
不恰当的强调会削弱句子的自然感。一篇作文用1-2处强调句就够了。
四、三弟：形式宾语（S + V + it + adj + to do / that）
这个结构不如前两个常见，但在写作中很实用——特别是表达”我认为/我发现/我觉得”的时候。
核心逻辑： 当宾语是to do结构或that从句时，用it代替宾语放在动词后面，把真正的宾语挪到后面。
对比：
-
❌ I find to learn English difficult.
-
✅ I find it difficult to learn English.（it代替to learn English）
-
❌ I think that he is right is true.
-
✅ I think it true that he is right.（it代替that从句）
写作中常用模式：
| 动词 | 结构 | 例子 |
|---|---|---|
| find | find it + adj + to do | I find it challenging to manage my time. |
| think | think it + adj + to do | Many students think it boring to memorize words. |
| consider | consider it + n/adj + to do | I consider it my duty to help others. |
| make | make it + adj + to do | Technology makes it easier to communicate. |
五、一张表区分三兄弟
| 特征 | 形式主语 | 强调句 | 形式宾语 |
|---|---|---|---|
| 开头是什么 | It is/was | It is/was | 主语 + 动词 |
| 去掉”it…that”后 | 句子不完整 | 句子完整 | 看情况 |
| 能否省略that | 不可省略（有些可） | 不可省略 | 可省略 |
| 主要功能 | 解决头重脚轻 | 突出信息重点 | 让宾语不臃肿 |
六、写作练习
把下面的句子改写成it句型：
-
To finish the work on time is very important. → It is very important to finish the work on time.
-
Tom broke the window.（强调Tom） → It was Tom who broke the window.
-
I find that learning a new language is fun. → I find it fun to learn a new language.
-
That the environment is getting worse is worrying. → It is worrying that the environment is getting worse.
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