Unit 3 Sea Exploration Discover Useful Structures 不定式复习 教案-2026-2027学年人教版（2019）高中英语选择性必修第四册

人教版（2019）选择性必修第四册  Unit 3 Discover Useful Structures

不定式复习  教案

 

教材分析

本节课是人教版（2019）选择性必修第四册 Unit 3 Sea Exploration 的 Period 2 Discover Useful Structures，语法点为动词不定式的综合复习。学生在初中和前面几个单元已经接触过不定式作主语、宾语、表语和宾补的基本用法，但对作定语和目的状语的结构掌握不牢，也容易把不定式和动名词作宾语的情况搞混。课本这部分以郑和下西洋与现代深海探测为载体，本节课紧扣单元海洋探索主题，以长江江豚保护与武汉滨江为情境重新组织例句和练习，让学生在熟悉的水域语境中梳理不定式的各种句法功能和语用差异。

教学目标

1. 通过观察例句，归纳不定式作主语、宾语、表语、定语、状语、宾补的六种形式与基本用法。

2. 在讲长江江豚、深海探测与武汉滨江水域的语境中正确运用不定式。

3. 区分不定式与动名词作宾语的不同，体会不定式表“目的/将来”的语用功能。

教学重难点

重点：不定式作定语和目的状语的结构与基本用法，以及与所修饰名词/主句的逻辑关系判断。

难点：① 不定式作定语时与所修饰名词的逻辑关系；② 不定式作宾补时与宾语的主动/被动关系判断。

 

Teaching Procedures

Step 1  Lead-in（约5分钟）

Teacher: Good morning, class. Today we're going to review infinitives. Let's start with the Yangtze and the creatures we all know in Wuhan. Look at the sentences and fill in the blanks with the correct form. Two minutes.

Look at the Yangtze scenes around Wuhan and fill in each blank with the correct form of the word in brackets.

1. The Yangtze River is a perfect waterway ______ (explore) by boat in summer.

2. The finless porpoise is said ______ (be) a living symbol of a clean Yangtze.

3. Wuhan scientists boarded the research ship early ______ (study) deep-sea creatures before the voyage.

【设计说明】用学生每天路过的长江和江豚引入，不急于讲规则，先让学生在熟悉的语境中感知不定式的三种位置——作定语、作主补、作目的状语。三种功能先混个脸熟，为后面的归纳攒感性认识。

Step 2  Analyze and Identify（约15分钟）

Task 1  Complete the sentences

Teacher: Now look at these sentences about the Yangtze and deep-sea exploration. Complete them with the correct infinitive form. Five minutes, then we check together.

1. The East Lake Ocean World is a good place ______ (learn) about deep-sea creatures.

2. Chinese scientists plan ______ (launch) another research vessel next year.

3. The best way ______ (understand) the ocean is to dive into it with a manned submersible.

4. We saw several porpoises ______ (leap) out of the Yangtze near the Wuhan Bridge.

5. The country has set up marine reserves ______ (protect) endangered species.

6. It is important ______ (study) the ocean before we exploit its resources.

【设计说明】这6句正好对应重点——前四句集中练定语、宾语和宾补（第1、3句是定语，第2句是宾语，第4句是宾补），后两句是目的状语和主语。先让学生独立填，做完直接核对答案，把六种功能里的重点几种先攒出来，为后面归纳功能做准备。这里重点突破“不定式作定语的两种位置”和“逻辑关系判断”。注意第4句see sb do sth是不带to的不定式作宾补，学生容易多加to，这里要当场点破。

Task 2  Identify the function

Teacher: Good. Now look at the six sentences again. Can you tell what function each infinitive serves in the sentence? Is it subject, object, predicative, attribute, adverbial, or object complement? Discuss with your partner. Three minutes.

【设计说明】让学生通过观察自己填过的句子，自己归纳不定式的六种句法功能，比一条一条讲规则印象更深。学生自己找出来的规律，后面总结的时候更容易记住。这里重点引导学生看定语那几句（第1、3句），当场点破判断口诀：不定式作定语找名词 → to do跟在名词后面补充说明它 → 就是定语。比如第1句a good place to learn，就是a good place that you can learn——直接切入难点①“定语的逻辑关系”。

Task 3  Complete the sentences with Chinese hints

Teacher: Now let's move on. Complete the following sentences according to the Chinese hints. Pay attention to the correct infinitive form. Four minutes.

1. 长江是武汉市民夏夜乘船游览的好去处。

The Yangtze is a good waterway for Wuhan residents ______ ______ by boat and ______ on summer nights.

2. 据说明年将下水一艘新的深海科考船。

A new research vessel is said ______ ______ ______ next year.

3. 科学家们早起是为了在日出前记录江豚的活动。

The scientists got up early ______ ______ the finless porpoises before sunrise.

4. 老师鼓励我们多读关于海洋探索的资料。

The teacher encouraged us ______ ______ more about sea exploration.

【设计说明】从单句填空过渡到汉语提示完成句子，难度稍升。第1句练定语，第2句练主补，第3句练目的状语，第4句练宾补——这里可以顺手补个对比：encourage sb to do sth（宾补，主动）和 sth to be done（被动宾补），帮基础弱的学生区分开。四个句子正好对应四个功能，学生写完就能感受到不同功能的位置差异。

Step 3  Summarize（约10分钟）

Task 1  Summarize the forms and functions

Teacher: Now work with your partner. Based on the sentences we just read, summarize the six functions of infinitives. I give you two minutes to think, then we share.

Basic form: to + v. (do)

• Subject (主语): To see is to believe. / It is + adj. + to do

• Object (宾语): want / hope / plan / decide + to do

• Predicative (表语): My dream is to...

• Attribute (定语): something to do / a place to visit

• Adverbial (状语): ... to do sth (表目的)

• Object complement (宾补): ask / tell / encourage sb to do sth

注意：see / hear / watch / notice / make / let / have 后面接不带to的不定式作宾补。

Task 2  Infinitive vs gerund after verbs

Teacher: Now think about this question. Which verbs take to do, and which take doing? Discuss in pairs.

【设计说明】形式总结放第二步之后，学生已经有了足够的例句支撑，归纳水到渠成。不定式和动名词作宾语的区别单独拿出来讨论，因为学生往往记不住哪些动词接to do、哪些接doing。这里必须把常见动词分类记牢：想要希望决定学习计划（want/hope/decide/learn/plan）接to do；享受完成练习建议（enjoy/finish/practise/suggest）接doing。

Step 4  Practice（约12分钟）

Task 1  Fill in the blanks

Teacher: Now practice. Complete the following sentences with the correct infinitive form of the words in brackets. Six minutes, then we check.

1. The submersible Jiaolong is a perfect tool ______ (explore) the deep sea.

2. Chinese scientists are working hard ______ (map) the floor of the South China Sea.

3. The best time ______ (watch) finless porpoises in Wuhan is early morning.

4. We noticed the porpoises ______ (jump) out of the water near the bridge.

5. It is our duty ______ (protect) the Yangtze and the oceans it feeds.

6. The country decided ______ (build) more research vessels for deep-sea missions.