语法讲练—It 作形式主语的句型
英语习惯用 It 作形式主语，把真正的主语放到句尾，让句子结构更平衡。
一、It is＋形容词＋for sb. to do sth.
形容词描述事情的性质（如 important，necessary 等），不是描述人的品质。
二、It is＋形容词＋of sb. to do sth.
形容词描述人的品质、性格（如 kind，nice 等），可以改写为 Sb. is＋形容词＋to do sth.。
三、It is＋形容词＋to do sth./that 从句
形容词描述事情，真正主语是不定式 to do 或 that 引导的从句。
四、It seems/seemed＋形容词＋for sb. to do sth.
【强化训练 1】用合适的 of/for/that 填空
1. It is beneficial us to do eye exercises every day to protect our eyesight.
2. It was admirable the volunteer to help the elderly in the community for years.
3. It is shocking the ancient pyramid was built without modern machines.

1. for
2. of
3. that

【分析】本题考查It作形式主语的核心句型用法，解题思路为：先明确三个句型的规则：①It is+形容词+for sb. to do sth.中，形容词描述事情的性质；②It is+形容词+of sb. to do sth.中，形容词描述人的品质；③It is+形容词+that从句中，that引导的从句为真正主语。再逐一分析每道题的形容词属性和句型结构，匹配对应规则选择合适的词。
【解析】1. 句中形容词beneficial（有益的）描述“每天做眼保健操”这件事的性质，符合It is+adj.+for sb. to do sth.的句型，故填for。
2. 句中形容词admirable（令人钦佩的）描述志愿者的品质，符合It is+adj.+of sb. to do sth.的句型，故填of。
3. 句中为It is+形容词+that从句的句型，that引导的从句是真正主语，故填that。
【答案】1. for 2. of 3. that
【知识点】It作形式主语的用法、for与of的辨析、that引导主语从句
【点评】本题是It作形式主语的基础语法练习题，聚焦核心句型的区分，是英语语法的基础考点，需准确掌握形容词修饰对象的判断方法，适合巩固语法基础。
【难度系数】0.4

【强化训练2】改写成 It 作形式主语的句子
1. You stayed up late to help me finish the project. (thoughtful)
→
2. We should form a good habit of reading every day. (necessary)
→
3. Tu Youyou discovered artemisinin and saved millions of lives. (great)
→

1. It is thoughtful of you to stay up late to help me finish the project.
2. It is necessary for us to form a good habit of reading every day.
3. It is great that Tu Youyou discovered artemisinin and saved millions of lives.

【分析】
要完成It作形式主语的句子转换，需先明确It作形式主语的三类核心结构：①当形容词描述人的品质（如thoughtful）时，用结构“It is + adj. + of sb. + to do sth.”；②当形容词描述动作的性质（如necessary）时，用结构“It is + adj. + for sb. + to do sth.”；③当真正主语是完整句子时，用结构“It is + adj. + that + 陈述句”。再结合每个小题的形容词类型和后续成分，匹配对应结构转换即可。
【解析】
1. 小题中形容词thoughtful描述人的品质，对应结构①，将原句主语You转换为of you，原句谓语stayed up late改为不定式to stay up late，其余部分保留，得到句子：It is thoughtful of you to stay up late to help me finish the project.
2. 小题中形容词necessary描述动作的性质，对应结构②，将原句主语We转换为for us，原句情态动词+动词原形should form改为不定式to form，其余部分保留，得到句子：It is necessary for us to form a good habit of reading every day.
3. 小题中真正主语是完整句子，对应结构③，将原句作为that引导的从句，得到句子：It is great that Tu Youyou discovered artemisinin and saved millions of lives.
【答案】
1. It is thoughtful of you to stay up late to help me finish the project.
2. It is necessary for us to form a good habit of reading every day.
3. It is great that Tu Youyou discovered artemisinin and saved millions of lives.
【知识点】
It作形式主语；形容词与of/for的搭配
【点评】
本题考查It作形式主语的不同句式转换，需根据形容词的语义属性和真正主语的形式选择对应结构，属于基础语法应用，需牢记三类结构的适用场景。
【难度系数】
0.4

Zhong Yang, a well-respected 1. (biology), died in a car accident. He spent his whole life researching plants and seeds, collecting many important seeds for China's seed banks. These banks protect plant seeds, 2. (especial) those for food, and stop important plants from disappearing forever.
Zhong Yang entered university at 15, first studying radio engineering, and later became interested in plants. 3. becoming a professor at Fudan University, plant and seed research became the focus of his life.
It is important for seed banks 4. (include) many different kinds of seeds. When Zhong Yang discovered that there was not enough research of the seeds from Xizang, he went there to collect seeds 5. (him). In 2001, he began his travels across Xizang. It was very difficult for him to brave the cold weather and great heights. He sometimes 6. (fall) sick, but he always continued with his work.
Zhong Yang knew it was 7. (good) to include more people when doing important work. He began a programme to find and train local students in field research to become scientists. Together, he and his team collected more than 40 million seeds from around 1,000 plants. Their hard work provided the world 8. lots of new information about the plants in China.
Zhong Yang left behind more than just a huge 9. (collect) of seeds. His love for his job and research lives on in his students. He once said, "My students 10. (continue) on the road of scientific exploration and the seeds we have collected may grow hundreds of years from now."

1. biologist
2. especially
3. After
4. to include
5. himself
6. fell
7. better
8. with
9. collection
10. will continue

【分析】
本题为英语语法填空题，需结合语境、词性变化、语法规则（如时态、固定句型、固定搭配等）逐个分析空格：1处需表示人的名词；2处修饰代词需用副词；3处根据上下文逻辑选介词；4处涉及固定句型；5处需反身代词；6处需过去式动词；7处需形容词比较级；8处为固定搭配；9处需名词；10处需一般将来时动词。
【解析】
1. 空格前有冠词a，需填表示人的名词，biology（生物学）对应的指人名词为biologist；
2. 此处修饰代词those，需用副词，故填especially；
3. 结合语境“在成为复旦大学教授后，植物与种子研究成为他的人生重心”，填介词After；
4. 固定句型“It is + adj + for sth to do sth”，故填to include；
5. 主语为he，需用反身代词表示“他自己”，填himself；
6. 全文叙述过去的事，用一般过去时，fall的过去式为fell；
7. 语境意为“做重要工作时包含更多人更好”，用good的比较级better；
8. 固定搭配“provide sb with sth”，故填with；
9. 形容词huge后需接名词，collect的名词形式为collection；
10. 引号内表述将来的动作，用一般将来时will continue。
【答案】
1. biologist
2. especially
3. After
4. to include
5. himself
6. fell
7. better
8. with
9. collection
10. will continue
【知识点】
英语语法填空、词性转换、固定搭配
【点评】
本题考查英语基础语法知识，涵盖词性转换、时态、介词、固定句型与搭配等，需结合语境运用语法规则解题，是常见的英语基础题型，注重对学生基础应用能力的考查。
【难度系数】
0.6