To find an expository text, start each paragraph with a mention of ah 45

The role of snow. Snowflakes are beautiful crystals that cling together in clumps as they fall, forming snow flakes. The size of a single snowflake is usually between millimeters.

Snowflakes are light, weighing only grams individually. No matter how light and small the snowflakes are, how wonderful they are, its crystals are regular hexagonal shapes, so the ancients had the saying that "there are more than five flowers of plants and trees, and six snowflakes are produced". How beautiful and light the snowflakes are!

I'm getting more and more fond of snowflakes, and it would be a pleasure to see the land covered with snow and the trees covered in silver again.

"Ruixue Zhaofeng Year" is a widely spread agricultural proverb in China. In the north, a thick, loose layer of snow covers wheat like a quilt to keep the wheat warm. The nitrogen in the snow is easily absorbed and utilized by crops.

The low temperature of snow water can freeze the pests that overwinter on the surface, and it also brings benefits to agricultural production. Therefore, there is another agricultural proverb: "In winter, the wheat covers the three-layer quilt, and the next year sleeps with steamed buns." ”

Snow has a wide range of effects, but snow has great benefits for humans. First of all, it is conducive to the growth and development of crops. Because snow conducts heat very poorly, the soil surface is covered with a snow cover, which can reduce the transfer of soil heat and block the invasion of cold air on the snow surface, so the crops protected by snow can safely overwinter.

Snow also stores water for crops. In addition, snow enhances soil fertility. It has been determined that every 1 liter of snow water contains about grams of nitrogen.

When snow water penetrates the soil, nitrogen fertilizer is applied once. Feeding livestock and poultry with snow water and irrigating crops can yield significant benefits.

Snow is both good and bad, and in the middle of spring in March and April, there is a sudden cold wave that causes heavy snowfall. It will cause freezing cold. Therefore, the agricultural proverb says: "Wax snow is a treasure, and spring snow is not good." ”

The role of snow on human health.

Medicine and Health News》 In winter, the snow is heavy and boundless. When people look at the jade tree and the flowers, they often ignore the role of snow. Snow has many benefits for human health.

The Compendium of Materia Medica has long recorded that snow water can detoxify and cure plague. There are no ones for snow water ** fire burns and frostbite.

Frequent bathing with snow water can not only enhance the resistance of ** and the body, reduce diseases, but also promote blood circulation and enhance physical fitness. If you drink clean snow water for a long time, you can live longer. This is one of the "secrets" of longevity in the deep mountains and old forests.

Why does snow have such a peculiar function? Because snow water contains less heavy water than ordinary water1 4. Heavy water can severely inhibit the life processes of living organisms.

Experiments have been conducted on fish that die very quickly in water containing 30 50 heavy water. The most basic condition for the formation of rain and snow is the existence of "condensation nuclei" in the atmosphere, and solid impurities such as dust, coal particles, and minerals in the atmosphere are the most ideal condensation nuclei. If the meteorological factors such as water vapor and temperature in the air meet certain conditions, the water vapor will condense into snowflakes around these condensation nuclei.

Therefore, snowflakes can wash a lot of pollutants in the air. Therefore, after a heavy snowfall, the air is exceptionally fresh.

The opening paragraph of the expository text serves as follows:

The opening paragraph of the expository essay uses descriptive language to vividly and vividly introduce the facts of the matter to be explained, and explain the main characteristics of the object; In terms of form, it mainly focuses on the role of the explanatory method, which can stimulate the reader's interest in reading, and lead to the following explanation of the topic of the article.

Expository essay is a genre of essay in which explanation is the main mode of expression. The explanation of objective things or the interpretation of abstract things makes people have a scientific understanding of the form, structure, nature, type, cause, function, relationship or concept, characteristics, evolution, and differences of things, and the center of the expository essay is clear and prominent, and the article is scientific, organized, and the language is accurate and vivid.

The three elements of an expository essay:

1. Rigor of content.

Truthfully reflect objective things, grasp the characteristics, essence and laws of things, and give readers a correct understanding.

2. The explanation is old-fashioned.

Writing chronologically is similar to a narrative; Write in spatial order to pay attention to the observation points, pay attention to the position and direction of the surface and inside, size, up and down, front and back, left and right, southeast, northwest, etc.; When writing in a logical order, we should pay attention to finding out the internal relationship between each part, from the surface to the inside, from the shallow to the deep, from the phenomenon to the essence.

3. Accuracy of language.

Representation of time, space, quantity, scope, degree, characteristics, nature, procedures, etc., all require accurate tracking of the age and the rise of the error. The language is concise, the explanations are rigorous, scientific and rigorous.

Question 1: How to write an expository essay and how to begin? General: Leads to the description object; stimulate readers' interest in reading; (There is descriptive language at the beginning, vividly leading to the things (affairs) that will be explained.)

The self-report of chopsticks.

I am a pair of chopsticks with a simple structure, born in ancient China, and have the honor of being called "China's Fifth Great Invention".

Plastic Bag I was born in a small factory as a small plastic bag. We were born with many brothers and sisters. Our birth provides many conveniences for human beings.

Since then, people have put down their vegetable baskets. All sorts of things were packed into our colorful bodies, and people were brought home, and we were so welcome. For a time, shopping malls, markets, streets, and parks could see us and people walking together.

We have become humanity's friendliest friends.

Question 2: How to write the beginning of an expository essay General:

elicit the description object;

and the hall brother to stimulate the reader's interest in reading;

There is descriptive language at the beginning, vividly leading to the things that will be explained

Question 3: How to write an expository essay and how to begin? General: Leads to the description object; stimulate readers' interest in reading; There is descriptive language at the beginning, vividly leading to the things that will be explained

The self-report of chopsticks.

I am a pair of chopsticks with a simple structure, born in ancient China, and have the honor of being called "China's Fifth Great Invention".

Plastic bag I was a small plastic bag, born in a small factory. We were born with many brothers and sisters. Our birth provides many conveniences for human beings.

Since then, people have put down their vegetable baskets. All sorts of things were packed into our colorful bodies, and people were brought home, and we were so welcome. For a time, shopping malls, markets, streets, and parks could see us and people walking together.

We have become humanity's friendliest friends.

Question 4: How to write the beginning of the expository essay 1Clarify the object of an expository essay and clarify the center of the explanation. (i.e., the characteristics of the thing being explained or the facts being explained.) ）

2.Clearly state the order, including chronological, spatial, and logical order.

Logical Order: 1: Phenomenon, Essence, 2, Major, Minor, 3, Generalization, Specific, 4, Cause, Effect, 5, From Characteristics Use.

3.Understand and analyze commonly used explanatory methods, including categorization, definition, examples, comparisons, numbers, analogies, etc.

4.Experience the characteristics of accurate and concise explanatory language, and understand the different characteristics of plain explanation and vivid explanation.

5.Grasp the structure of expository essays, mainly including the total score relationship, the juxtaposition relationship and the progressive relationship.

6.The language characteristics of the expository text: accurate, concise, plain, vivid and rigorous.

Question 5: How to write the beginning of an expository essay General:

elicit the description object;

stimulate readers' interest in reading;

There is descriptive language at the beginning, vividly leading to the things that will be explained

First, the beginning. 1. Self-explanatory.

Use the beginning of the self-description to make the expository text.

The language is intimate and natural, and quickly shortens the distance with the reader.

Example: My name.

It's called glasses, and I'm sure everyone knows me. But not everyone knows me well, so in order to become friends with you, I would like to introduce myself first. I mainly consist of two parts: one is the frame and the other is the lens. ("Glasses").

2. Contrasting.

Beginning with a comparison can make the characteristics of the object more distinct and prominent in the contrast.

Example: We all know that most plants get their food in their autotrophic form, but pitcher plants.

No. There are three to four hundred species of plants in the world that eat animals, and pitcher plants are one of them. ("Meat-Eating Plants - Nepenthes").

The role of the first paragraph: This kind of question has different angles:

By ......The method of explanation illustrates the ......(the characteristics or facts of things) to make the explanation ......(Role).

What the common illustrative methods do:

Examples: Illustrate the characteristics of things by giving concrete examples, so as to make the explanation more concrete.

Categorization: Categorize the characteristics of things and explain them into categories to make the explanation more organized.

Comparison: Comparing and contrasting highlights the characteristics of things.

Analogy: Compare it to a thing, so as to vividly illustrate the characteristics of things.

Definition: To use concise and scientific language to reveal the object of explanation, scientific facts, so as to reveal the characteristics of things in a more scientific, essential, and general way.

Column numbers: Use specific data to explain the characteristics and facts of things, so that the explanation is more accurate.

Column charts: Use column charts to explain the characteristics and facts of things, so that the explanations are more concise and intuitive.

Citation: Quotation notes come in the following forms

a. Cite specific examples; (The role is the same as that of examples).

b. Cite specific data; (Functions in the same column).

c. Quoting famous sayings, aphorisms, proverbs; The effect is to make the explanation more convincing.

d. Quoting myths and legends, news reports, riddles, anecdotes, etc. The effect is to make the description more interesting. (The citation at the beginning of the article also serves to elicit the object of the explanation; The function of arousing the reader's interest in reading. ）

Explain the object and content of the explanation. Which leads to the following... Details).