You probably don't think about soil often, but the following report may help you learn about science of soil.
What is soil made of?
Soil is made of sediments (沉积物) and humus(腐殖质). Sediment is small pieces of rock broken down over time by rain, ice, and wind. Sediment is often found in water. Humus comes from decayed(腐烂的) plants and animals. It helps give plants a lot of the food they need to grow.
How does soil form?
Over centuries, rock breaks down into very small pieces.
The rock pieces mix with humus.
The humus gets thicker and thicker over time. Soil is formed(形成)l
How are soils different?
Soils can be different colors and have different textures(质感). Texture is how the surface of an object feels. Color and texture are two features(特征) of soil.
Plants and soil
Plants do not grow well in some soils. Sandy soi1 is too dry. It does not hold water. Soil with too much clay is too thick. Most plants grow well in dark, rich garden soil that has different sediments and a lot of humus in it.
The title （标题）： ____ |
The things in soil | Sediment is often found in water. Humus ____ decayed plants and animals. |
The steps of forming | Rock breaks down into very small pieces. The rock pieces mix with humus. The humus gets ____ . |
____ | Soils can be different colors and have different textures. |
The relationship between plants and soil | ____ is good for plants to grow in. |
，其苯环上的二溴代物有9种同分异构体，由此推断A苯环上的四溴代物的同分异构体的数目有