How to write a good expository essay, how to write an expository essay

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 very light, with a single weight of only - grams.

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." ”

There are two ways to write expository essays: outline, descriptive, and question-asking.

1. Overview.

At the beginning, an overview of things is introduced in concise language to give a general image. For example, "The Palace Museum" begins like this: In the center of Beijing, there is a city within a city, which is the Forbidden City.

Now people call it the Forbidden City, also known as the Palace Museum. The Forbidden City was the imperial palace of the Ming and Qing dynasties. It is the largest and most complete ancient palace complex existing in our country, which has been around for more than 500 years.

2. Descriptive.

The beginning describes the characteristics of things, so that the reader has an intuitive overall understanding. For example, the beginning of "Chinese Stone Arch Bridge" describes it like this: the bridge hole of the stone arch bridge is arc-shaped, like a rainbow.

In ancient mythology, it is said that the rainbow after the rain is a "bridge between heaven and earth", and you can go to heaven through the rainbow. The poets of our country compare the arch bridge to the rainbow, saying that the arch bridge is "lying rainbow" and "flying rainbow", and the water arch bridge is described as "Changhong lying wave".

3. Questioning.

The opening question can stimulate the reader's desire and interest in knowledge, and be eager to understand things or things. Such as the first paragraph of "Why Are Flowers So Red". By describing the brightness and beauty of safflowers, the question of "why flowers are so red" is naturally raised, so that people can understand the reasons for it and explore its knowledge with the author's specific explanation.

Fourth, the definition.

Begin to define things, suggest the connotation (essential characteristics) and extension (scope of containment) of things, and let people understand the essence of things. For example, the beginning of "The Coordination Method" defines things as follows: "The overall planning method is a mathematical method for arranging the work process, and its practical scope is extremely wide. ”