搞懂 It 作形式主语的用法,提升句型复杂度与英语表达专业度。
🌟 一、什么是形式主语?
在英语中,有些句子为了突出主语后的不定式或从句,会使用 “It” 作为形式主语,把真正的主语(如动词不定式、动名词、从句)放在后面。
✅ 举例:
- It is important to speak clearly.
真正的主语是 “to speak clearly”,但为了句子更流畅,前面用了 It 作形式主语。
🧩 二、常见结构形式
句型结构 | 示例 |
---|---|
It + be + 形容词 + to do sth. | It is necessary to review your notes. |
It + be + 形容词 + that 从句 | It is obvious that he is wrong. |
It + takes + 人 + 时间 + to do sth. | It took me two hours to finish the task. |
It + is + 时间/距离 + to/from… | It is five minutes to the station. |
💡 三、与强调句型的区别?
虽然 It 也用于强调结构(It is…that/who…),但在形式主语句型中,It 只是形式占位,真正主语在后。
对比:
- It is important to study English. ✅(形式主语)
- It is English that he studies. ✅(强调句型)

📝 四、典型例句分析
🔹 It is difficult to learn Chinese.
🔹 It is strange that she didn’t show up.
🔹 It took him an hour to clean the room.
🔹 It is not clear whether they’ll come.
✅ 提示:形式主语句型可用于表达判断、感受、必要性等抽象评价,使句子更正式。
🚫 五、常见错误归纳
错误表达 | 正确表达 | 原因说明 |
---|---|---|
To finish the work is difficult. | It is difficult to finish the work. | 主语位置突兀,需使用形式主语结构 |
That he failed is shocking. | It is shocking that he failed. | 主句信息过长,建议使用 It 占位 |
✍️ 六、写作与练习建议
📌 在 写作中 使用 It 作形式主语,可以:
- 增加句型多样性
- 提升文章表达层次
- 避免重复简单句
📝 练习任务(可提交至训练系统):
请将以下句子改写为形式主语句型:
- To master English is important.
- That he lied surprised everyone.
- Finishing the project on time is necessary.
It 作形式主语的句型,不仅让句子表达更地道,还能增强书面表达的严谨性与条理性。如果你希望在写作中实现句式跃升、打破语法瓶颈——
👉 【李校来啦智能英语训练系统】的“形式主语专项训练模块”,提供句型改写建议、AI语法批改与结构推荐,助你构建更有深度的英语句式!
