试题题干
Translate the following sentence into Chinese.
Each field is covered by a limited amount of topsoil, the upper layer of earth which is richest in the nutrient and minerals necessary for growing crops.
参考答案
试题解析
考点：topsoil (n.) 表土层；nutrient (n.) 营养物。
句子结构：句子主干为Each field is covered by topsoil，the upper layer of earth···修饰topsoil。