考研英语中的形式主语通常出现在句子结构中，用以替代真正的主语，使句子读起来更加流畅或符合语法规范。以下是一些常见的考研英语形式主语：
1. It作形式主语，真正的主语是动词不定式、动名词或从句。
- It is important to finish the project on time.
- It is necessary to review the notes before the exam.
2. It作形式主语，真正的主语是形容词或名词短语。
- It is a great pleasure to meet you.
- It is a significant discovery that will change our understanding of the universe.
3. It作形式主语，真正的主语是介词短语。
- It is from this book that we learn the most about ancient civilizations.
- It is by reading widely that we can broaden our horizons.
4. It作形式主语，真正的主语是副词。
- It is not unusual to see such a scene in the city.
- It is only after careful consideration that we can make the best decision.
掌握这些形式主语，有助于提高考研英语的语法水平。现在，推荐一款考研刷题小程序：【考研刷题通】，它涵盖了政治、英语、数学等全部考研科目，是考研路上的得力助手。立即加入我们，开启高效刷题之旅！【考研刷题通】——考研路上的好帮手！