词类又叫词性，英语单词根据其在句子中的功用，可以分十个大类。
词类 | 英语名称 | 作用 | 例词 |
名词 | Noun（缩写为n.） | 表示人或事物的名称 | party政党 China中国 |
代词 | Pronoun (pron.) | 用来代替名词、形容词或数词等 | He他 that那 |
数词 | Numeral (num.) | 表示数量或顺序 | one一 first第一 |
形容词 | Adjective（adj.） | 用来修饰名词，表示人或事物的特性、性质 | safe安全 great伟大 |
副词 | Adverb (adv.) | 用来修饰动词、形容词或其他副词，表示动作或形状的特性 | hard艰苦 here这里 |
冠词 | Article (art.) | 用在名词前，帮助说明名词所指的人或事物 | an，a，the |
动词 | Verb (v.) | 表示人或事物的动作或状态 | eat吃 have有 |
介词 | Preposition (prep.) | 用在名词、代词等前面，说明句子中词与词之间的关系 | under在。。。。。。下 in在。。。。。。里 |
连词 | Conjunction (conj.) | 用来连接词、短语或句子 | and和 but但是 |
感叹词 | Interjection (interj.) | 表示说话时的感情或口气 | Hello喂 why呃，嘿 |
In answer to the final question about the importance of rainforest conservation, the majority of children simply said that we need rainforests to survive（宾语从句）. Only a few of the pupils (6%) mentioned that rainforest destruction may contribute to global warming（宾语从句）. This is surprising considering the high level of media coverage on this issue. Some children expressed the idea that the conservation of rainforests is not important（同位语从句）.
The result of this study suggest that certain ideas predominate in the thinking of children about rainforests（宾语从句）. Pupils’responses indicate some misconceptions in basic scientific knowledge of rainforests’ ecosystems such as their ideas about rainforests as habitats for animals, plants, and humans and the relationship between climatic change and destruction of rainforests.
Pupils did not volunteer ideas that suggested （定语从句）that they appreciated the complexity of causes of rainforestdestruction（宾语从句）. In other words, they gave no indication of anappreciation of either the range of ways in which（定语从句）rainforests are important or the complex social, economic and political factors which drive the activities （定语从句）which are destroying the rainforests（定语从句）. One encouragement is that the results of similar studies about other environmental issues（表语从句）suggest that older children seem to acquire the ability toappreciate, value and evaluate conflicting views（宾语从句）. Environmental education offers an arena in which these skills can be developed（定语从句）, which is essential for these children as future decision-makers（非限定性定语从句）.
上边的三段话节选自雅思阅读真题，我们以其中出现的单词为例，来关注以下不同词性的词在句子中扮演的角色。注意图中阴影部分颜色相同的词，它们本身的词性不同，在句子中出现的位置、扮演的角色也是不同的。
先看看文中带家属的词吧~（阴影部分颜色相同的是一家哒）
同根词
1. importance（n.）—— important（adj.）
2. indicate（v.）—— indication（n.）
3. appreciated（v-ed）—— appreciation（n.）—— appreciate（v.）
4. complexity （n.）—— complex（adj.）
5. destruction（n.）—— destroying（v-ing） （注：长得不是很像，但是确实是一家人哦！）
这些本属一家的单词，分工都很明确的。充当不同的角色，就要派出不同的词，可不能派错词哦，不然歪果仁会认为我们用错词啦~
这些词是不是可以用上我们的改编版《三字经》了呢 —— “词之初，性本异。形相近，性相远。”
除了这几个词以外，文中还有一些词也是需要我们注意的。虽然它们今天没有带家属，但是我们也要认识它们家属中常出现的几位呢（文中红色字体的单词）。也有一些单词比较厉害，集几种词性于一身，我们主要看它们常用的词性。
其他常见同根词
conservation（n.保护，保存）—— conserve（v.）—— 注意与conversation（对话，交谈）区分开
majority（n.大多数）—— major（adj.）—— 注意与之对应的minority（n.少数人）
survive（v.幸存，生存）—— survival（n.）
coverage（n.报道，不是“覆盖”哦）—— cover（v.）
responses（n. 反应，回答）—— respond（v.）
scientific（adj. 科学的）—— science（n.）
climatic（adj. 气候的）—— climate（n.）
volunteer（v. 自愿提出。作n.“志愿者”也是很常见的）——voluntary（adj.）
social（adj. 社会的）—— society（n.） 注意其发音 /sə'saɪətɪ/
economic（adj. 经济的） 注意重音 /iːkə'nɒmɪk/ —— economy（n.） 注意重音 /i'kɔnəmi/
political（adj. 政治的）—— policy（n. 政策）—— politics（n.政治学）
encouragement（n. 鼓励）—— encourage（v.）—— 可把“ment”名词后缀，如management、development等
environmental（adj. 环境的）—— environment（n.）/ɪn'vaɪrənm(ə)nt/（注：这个单词不管是发音还是拼写，都要保证准确无误！）
词性练习
(1).重要，重要的
1. Anybody can see the _________ of good health.
2. It is __________ to see that the brakes on your bicycle work properly.
3. More ______ _____, the teacher should make the total meaning of the dialogue clear to the students before having them repeat it.
( 2 ) 发明，创造
1. Necessity is the mother of __________.
2. He __________ a story to explain why he was late.
3. It was absolutely new method __________ by himself.
( 3 ) 兴趣，使发生兴趣，有趣的，引起兴趣的
1. Geology __________ him.
2. He’s a most __________ man.
3. He did not seem at all __________ in the subject.
4. I will be most __________ to hear your personal views on the station there.
5. Local color added __________ to the novel.
( 4 ) 善良，好心，仁慈，和蔼
1. I want to thank you for your __________ to me.
2. The policeman treated the lost child __________.
3. Taking a blind man across the street is a __________ act.
4. Will you be so __________ as to answer a few questions?
( 5 ) 迟，晚；后来，最近，最新
1. I was __________ getting up this morning.
2. Tom came to school __________ and missed the first lesson.
3. Nine months __________, they were divorced.
4. They have equipped the office with the ___________ business machines.
5. What have you been doing ___________.
( 6 ) 生命，生活，谋生；活的，活着的；生动的，活泼的
1. Eat to __________, but do not __________ to eat.
2. Because of all the arguments the meeting was a __________ one.
3. Language is a __________ and continually changing thing.
4. He earns his __________ by growing rice.
5. Many people lost their ___________ in the accident.
( 7 ) 爱，喜爱；可爱，好看，美好
1. How ________ your roses are looking.
2. It was a __________ garden, with soft green grass.
3. Though his income was small, he ________ to buy books.
( 8 ) 领导，领先，首先，领袖，领导人
1. Our football team has a __________ of two goals.
2. The blind man had a dog to ___________ him.
3. What __________ you to think that?
4. Our __________ led us through the forest.
5. What the country needs most is wise __________.
(9) 主要，主要部分；主要的；主要地，大部分
1. He is the __________ character in the story.
2. Our __________ meal is in the evening.
3. His money comes __________ from business interests.
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