一、主语从句讲解
（一）定义
在复合句中充当主语的从句叫作主语从句，整体相当于一个名词；分两种结构：从句放句首作主语 / 用it作形式主语，真正主语后置。
三条硬性规则
1. 连词that无词义、不作成分，绝对不能省略；
2. whether表“是否”可引导主语从句放句首，if不能置于句首引导主语从句；
3. what/whatever/who/whoever等连接代词在从句中充当主/宾/表；when/where/why/how连接副词在从句作状语。
（二）引导词分项讲解
1. that（只起连接，无含义，从句主谓完整）
例句：That we should protect traditional culture is important.
解析：从句we should protect traditional culture主谓齐全，只需要连接词that。
2. whether（表“是否”，可放句首/用于it形式主语结构）
例句：Whether humans can live on Mars is still unknown.
解析：表达不确定“是否”，主语从句置于句首，不用if。
3. what / whatever（指代事物，在从句做主/宾，译为“……的事物”）
例句：What we learn in class lays a foundation for our future.
解析：从句缺少宾语，指代学到的东西，用what。
4. who / whoever（指代人，who特指某人；whoever泛指“任何……的人”）
例句：Whoever devotes himself to teaching deserves respect.
解析：whoever在从句作主语，泛指所有投身教育的人。
5. whose（表所属，后接名词，极少考主语从句，了解即可）
6. when / where / why / how（连接副词，从句主谓完整，缺对应状语）
例句：How space plants grow interests many scientists.
解析：从句结构完整，缺少方式状语，用how。
（三）重难点：it作形式主语四大必考句型
真正主语过长时，用it放在主句主语位置占位，主语从句放句尾。
1. It + be + 形容词 + that从句
It is clear that online learning has both advantages and disadvantages.
2. It + be + 名词短语 + that从句
It is a fact that many students struggle with self-study at home.
3. It + 被动语态 + that从句（固定背诵）
It is said that…据说 / It is reported that…据报道 / It is believed that…人们认为
4. It + 不及物动词 + that从句
It turns out that…结果是 / It happens that…碰巧 / It occurs to sb. that…某人突然想到
（四）易混辨析：that vs what
1. 从句主谓完整，不缺成分 → 只用that
That kids lack self-discipline troubles many parents.
2. 从句缺少主语/宾语 → 用what
What worries teachers most is students’ low learning efficiency at home。
二、填空专项
第一部分：12道高考真题改编题
1. 【2025全国一卷】____ makes Go popular worldwide is its deep cultural meaning.
2. 【2025九省联考】____ we can balance study and rest is a key problem for high school students.
3. 【2025新题·汤显祖】____ Tang Xianzu created great plays is widely recognized by people.
4. 【2022新高考II卷】____ parents cannot manage their children well is a common social phenomenon.
5. 【2025全国二卷】It remains unknown ____ more after-school classes will be allowed in the future.
6. 【2023新高考II卷】It is obvious ____ self-study at home is not suitable for most teenagers.
7. 【2022全国乙卷】____ International Tea Day spreads tea culture draws global attention.
8. 【2021新高考I卷】____ Huangshan has amazing sea of clouds attracts thousands of tourists every year.
9. 【2024全国甲卷】____ made Yellowstone the first national park was people’s love for nature.
10. 【2022全国甲卷】____ Cao and Wu cleaned rubbish along the Silk Road won high praise.
11. 【2023新高考I卷】____ can help students keep learning efficiency is systematic class teaching.
12. 【2021全国完形同源】It is reported ____ most students lack self-control during holidays.
第二部分：原创综合题
13. ____ matters most to students is steady learning progress.
14. ____ every student can finish homework on time troubles many teachers.
15. It is clear ____ private tutoring widens the gap between students.
16. ____ we study decides our future development.
17. It remains uncertain ____ holiday courses will be opened uniformly.
18. ____ improves students’ thinking is sufficient in-class training.
19. It is a truth ____ self-disciplined kids are only a small minority.
20. ____ parents worry about is their children’s poor study state at home.
21. It is said ____ secret after-school training breaks educational fairness.
22. ____ helps students solve difficult problems is face-to-face teaching.
23. It occurs to many teachers ____ fewer classes make students fall behind.
24. ____ can stick to learning without supervision deserves praise.
25. It turns out ____ most teenagers can’t calm down while studying alone.
26. ____ we lack at home is timely guidance from teachers.
27. It is believed ____ unified holiday classes benefit all students equally.
28. ____ makes learning hard is the shortage of targeted exercises.
29. It happens ____ some students hide their tutoring experience from teachers.
30. ____ every teacher hopes for is students’ active learning attitude.
31. ____ annoys teachers most is students’ careless learning at home.
32. ____ saddens many parents is their kids’ low concentration at home.
33. ____ puts ordinary students at a disadvantage is unregulated private tutoring.
34. ____ worries frontline teachers is the unfair competition caused by secret make-up classes.
35. ____ makes education unfair is the difference in after-school training chances.
36. ____ is suitable for senior high students is enough systematic classroom teaching.
37. It is a pity ____ many kids can’t ask teachers questions while studying at home.
38. ____ destroys educational balance is hidden private tutoring everywhere.
39. ____ makes teachers tired is the great gap between students’ learning conditions.
三、完整参考答案
第一部分：12道高考真题改编题
1. 答案：What
解析：从句缺少主语，指代“让围棋风靡世界的事物”，用what引导主语从句。
2. 答案：Whether
解析：主语从句置于句首，表达“是否”，表不确定，不用if。
3. 答案：That
解析：从句Tang Xianzu created great plays主谓结构完整，仅需连接词that。
4. 答案：That
解析：从句语义完整，that引导主语从句，阐述客观现象。
5. 答案：whether
解析：it作形式主语，真正主语后置，unknown表不确定，用whether。
6. 答案：that
解析：固定句式It is obvious that…，that引导后置主语从句。
7. 答案：That
解析：从句结构完整，that引出整件事作主语。
8. 答案：That
解析：从句主谓齐全，that引导主语从句作句子主语。
9. 答案：What
解析：从句缺少主语，指代“促成黄石国家公园诞生的事物”，填what。
10. 答案：That
解析：从句表意完整，that引导整件事作主语。
11. 答案：What
解析：从句缺少主语，指代“能维持学生学习效率的事物”，用what。
12. 答案：that
解析：固定句型It is reported that…，that引导后置主语从句。
第二部分：原创综合题
13. What；从句缺主语，指代核心要素
14. That；句子成分完整，that引导整件事作主语
15. that；It is clear that 标准形式主语从句结构
16. What；what充当study的宾语，表学习的内容
17. whether；uncertain表不确定性，形式主语结构用whether
18. What；从句缺少主语，指代提升思维的内容
19. that；It is a truth that固定主语从句句型
20. What；worry about缺少宾语，what指代担忧的事情
21. that；It is said that经典形式主语结构
22. What；从句主语空缺，指代答疑方式
23. that；It occurs to sb. that固定句式
24. Whoever；泛指任意能自律自学的人，从句主语
25. that；It turns out that 固定句型
26. What；lack缺少宾语，指代欠缺的帮助
27. that；It is believed that大众观点句型
28. What；句子主语缺失，指代学习困难的原因
29. that；It happens that 主语从句固定搭配
30. What；hope for缺少宾语，指代期待的内容
31. What；从句缺少主语，指代困扰老师的事情
32. What；主语空缺，指代让家长难过的事
33. What；充当从句主语，指代不利因素
34. What；作从句主语，代表教师担心的问题
35. What；主语位置空缺，指代教育不公的源头
36. What；从句缺少主语，适配高中生的学习内容
37. that；It is a pity that遗憾类形式主语从句
38. What；破坏教育平衡的因素，从句主语
39. What；造成教师疲惫的原因，从句主语
