model of economic order quantity

例句：

1. 1. The scientist used a model to explain the process of photosynthesis.
   科学家用一个模型来解释光合作用的过程。
2. 2. He is a model student who always performs well in exams.
   他是一个表现优异的模范学生，考试总是考得很好。
3. 3. The model is expected to be released next month.
   这个模型预计将在下个月发布。