The mineral particles found in soil range in size from microscopic clay particles to large boulders. The most abundant particles - sand, silt, and clay - are the focus of examination in studies of soil texture. Texture is the term used to describe the line composite sizes of particles in a soil sample, typically several representative handfuls . To measure soil texture, the sand, silt, and clay particles are sorted out by size and weight. The weights of each size are then expressed as a percentage of the sample weight.
In the field, soil texture can be estimated by extracting a handful of sod and squeezing the damp soil into three basic shapes; (1) cast, a lump formed by squeezing a sample in a clenched fist; (2) thread, a pencil shape formed by rolling soil between the palms; and (3) ribbon, a flatfish shape formed by squeezing a small sample between the thumb and index finger. The behavioral characteristics of the soil when molded into each of these shapes, if they can be formed at all, provides the basis for a general textural classification. The behavior of the soil in the hand test is determined by the amount of clay in the sample. Clay particles are highly cohesive, and when dampened , behave as a plastic. Therefore the higher the clay content in a sample, the more refined and durable the shapes into which it can be molded.
The author mentions "several representative handfuls" in the passage in order to show ______.
Hãy suy nghĩ và trả lời câu hỏi trước khi xem đáp án
Lời giải:
Báo saiĐáp án A
Ta có thể tìm thấy câu trả lời qua câu sau trong bài: “Texture is the term used to describe the line composite sizes of particles in a soil sample, typically several representative handfuls.” (Kết cấu là thuật ngữ được sử dụng để mô tả các quy mô hỗn hợp theo hàng của các hạt trong một mẫu đất, điển hình là một vài nắm đất đại diện làm mẫu).
Như vậy cụm từ “several representative handfuls” được tác giả đề cập trong bài để chỉ các loại mẫu đất (the range of soil samples).