求翻译：这主要是因为任何一种模型都是直接或间接的依据历史数据来建模，而一个复杂的经济系统，随着时间的推移，与历史数据相联系的内部及外部环境条件会产生各种变化。是什么意思？

This is mainly because of a model are directly or indirectly based on historical data to model a complex economic system, over time, internal and external environmental conditions associated with the historical data will produce a variety of changes .

This is mainly because of any one type of model is a direct or indirect of the basis of historical data for modeling, and a complexity of the economic system, as time goes by, associated with the historical data for internal and external environmental conditions can have a variety of changes.

This mainly is because any kind of model all is direct or the indirect basis history data comes the modelling, but a complex economical system, along with the time passage, the interior and the external environment condition which relates with the historical data can have each kind of change.

This is mainly because any model is based on historical data, directly or indirectly, to modeling, and a complex economic system, with the passage of time, associated with historical data will produce a variety of internal and external environmental conditions change.

正在翻译，请等待...