• 报告 Report
  • 说明 Explanation
  • 议论 Arguments


Classifying and describing things.


  • 分类 Classifying
  • 描述 Descriptive
  • 组成 Compositional

Classifying 分类


Eruptions of volcanoes may be divided into three main types: (1) the explosive type, in which rock fragments are thrown out with explosive violence; (2) the quiet type, in which hot liquid rock quietly flows on the surface; (3) the intermediate type, in which eruptions are at times violent and at other times consist of the quiet outflowing of lava.


  • 表达类别:types/kinds/classes/categories/sorts/varieties…
  • 表达组成:consist of/comprises/can be divided into…
  • 划分依据:according to/on the basis of/depending on

Descriptive 描述


Ergonomics (人体工程学) can be defined as the design of work so that the best is made of human capabilities without exceeding human limitations.

The evolution of a product or design based on ergonomics relates the product or design to the physical needs of the user. These physical needs include not only size and position but other aspects such as floor surfaces, illumination levels, hand grips, switch standards and vision.

Understanding the physical needs of the user allows the designer to cater for individual differences and to create products that cater for the needs of the majority of consumers. Ergonomics is to do with the human body as a whole but it also involves the function of parts of the body and the ease with which humans perform simple tasks.


  • 位置(position):adjacent to/alongside/opposite/parallel to…
  • 结构(structure):nailed/screwed/fastened/connected…
  • 形状(shape):square/round/oval/irregular…width/height/diameter…
  • 功能(function):function/purpose/aim…
  • 特点(properties):light/tough/elastic/flexible/transparent…

Compositional 组成



(classification)Atoms are the units for elements. (components)The atom is basically composed of electrons, protons, and neutrons. (definition)The electrons, protons, and neutrons of one element are identical to those of any other element. There are different kinds of elements because the number and the arrangement of electrons and protons are different for each element.

(function)The electron carries a small negative charge of electricity. The proton carries a positive charge of electricity equal and opposite to the charge of the electron. Both the electron and proton have the same quantity of charge, although the mass of the proton is approximately 1,827 times that of the electron. In some atoms there exists a neutral particle called a neutron. The neutron has a mass approximately equal to that of a proton, but it has no electrical charge. According to theory, the electrons, protons, and neutrons of the atoms are thought to be arranged in a manner similar to a miniature solar system. Notice the helium atom in the figure. Two protons and two neutrons form the heavy nucleus with a positive charge around which two very light electrons revolve. The path each electron takes around the nucleus is called an orbit. The electrons are continuously being acted upon in their orbits by the force of attraction of the nucleus. To maintain an orbit around the nucleus, the electrons travel at a speed that produces a counterforce equal to the attraction force of the nucleus. The orbiting electrons do not follow random paths, instead they are confined to definite energy levels. Visualize these levels as shells with each successive shell being spaced a greater distance from the nucleus.


Explaining how processes happen. 先描述现象(phenomenon),再进行阐述(explanation)。


  • 顺序型 Sequantial
  • 一果多因型 Facorial
  • 一因多果型 Consequantial
  • 条件型 Conditional

Note:写这类文体时,文中不一定要出现因果连接词(because, so, therefore…),可以通过自然逻辑关系串接。

Sequantial 顺序型


(Phenomenon)Many of the wetlands of the north have been formed by the large rivers that flow from the rugged escarpments that fringe the Top End coastline.

(Explanation)In the wet season huge volumes of water flow from the escarpments. When this water hits the flood plains it slows down and spreads out forming the wetlands. The wetlands border the sea, however a series of sand ridges stopped sea water flowing into the wetlands. This kept the wetland water fresh.

Factorial 一果多因型


(Phenomenon)How can plant life grow so well in such dry, hot and infertile places? The mulga tree likes long droughts – if it is too wet mulga trees will not grow.

(Explanation)The shape of the mulga tree is the key to it surviving dry times. The branches of the mulga fan out from the bottom – like a huge half moon. The branching leaves and stem catch the rain and it trickles down to the soil. This traps more rainfall than if the tree grew straight up. The mulga catches more water than a gum tree. The water is stored in the soil to be used by the tree during the next drought. Even the mulga’s leaves help it to survive the drought. They are a silvery grey colour. The sun’s rays bounce off the leaves helping the plant to stay cool. Also the mulga tree makes its own food by dropping thousands of leaves


  • A-B因果:contributes to/due to/lead to/result in/give rise to/caused by
  • 句子关联:therefore/consequently/As a result

Consequantial 一因多果型


(Phenomenon)In southern Australia the woodlands have been cleared to plant crops like wheat and other cereals. Sheep and cattle are grazed on introduced pastures.

(Effect - tree death)When the land was first cleared small clumps of trees or single trees were left for shade. Today these trees are reaching the end of their lives and dying.

(Effect -soil erosion)The clearing of the trees has caused problems in using the land for farming. Without trees the land has been eroded by wind and rain. Today farmers are replanting the trees to try to stop this erosion.

(Effect - habitat loss)Animals like the common dunnart(一种袋鼠) rely on the fallen logs for shelter. The logs of old trees have hollows in them and the small animals of the woodlands hide in these. If these logs are cleared and removed the animals no longer have places to shelter.

Conditional 条件型


(Phenomenon)If the object is completely submerged,it displaces its own volume of fluid. The weight of displaced fluid, and therefore the upthrust, will depend on the density of the fluid.

(Condition 1) If the density of the fluid is less than the average density of the object, the weight of the displaced fluid will be less than the weight of the object and the object will sink.

(Condition 2) If, on the other hand, the density of the fluid is greater than the average density of the object, the weight of the displace fluid will therefore exceed the weight of the object. The net upward force will then cause the object to rise to the surface where it will float.



Exposition通常是围绕一个中心点(central idea)展开的文章,会从几个不同的points出发,最后作总结。

Discussion通常看起来较为客观(seem to be objective),会同时讨论两个或多个观点,并给出自己的倾向。