求翻译：通常可以根据各类食物所能提供的能量及各种营养素的数量和比例来衡量膳食结构的组成是否合理。一个地区膳食结构的形成与当地生产力发展水平，文化、科学知识水平以及自然环境条件等多方面的因素有关。不同历史时期、不同国家或地区、不同社会阶层的人们，膳食结构往往有很大的差异。是什么意思？

Can often be the number and proportion of the various types of food can provide energy and nutrients to measure the composition of the diet structure is reasonable. A dietary pattern in the formation and local development level of productivity, culture, level of scientific knowledge, as well as natu

Based on various types of food can usually provide the energy of all kinds of nutrients and the amount and proportion of the diet to measure composition is reasonable. A meal structural areas of the form with the local development of the productive forces, culture, and scientific knowledge as well a

Usually may act according to the energy and each kind of nutrient quantity and the proportion which each kind of food can provide weighs the meals structure the composition is whether reasonable.A local meals structure formation and the local productive forces level of development, the culture, the

Can usually be under all kinds of food can provide energy and nutrients by the number and the scale to measure the composition of the diet is reasonable. A dietary structure in the formation and development of local productive forces level, culture, scientific knowledge, as well as the natural envir