[语篇解读] 本文是一篇科普文，介绍了土壤的构成与土壤的pH对于植物生长的影响。
1．The layer of soil that provides necessary nutrients for plant growth is called________.
A. litter B. topsoil
C. humus D. subsoil
[解析] 考查细节理解。根据文章第二段中的“The topsoil layer is made up of small particles of rock mixed with rotten plant...which is black and gives the topsoil its dark colour.This layer is usually rich in nutrients”可知给植物提供必要营养的土层是topsoil layer。
[答案] B
