what is the company's principal field of activity如何翻译

这家公司主要的经营领域是什么？（结合上下文看看是什么类型的公司）

这家公司的主要研究领域是什么？

have as one's principal field of study.
作为一个人主要的学习对象.
Apart from ensuring that the Fund meets its statutory roles,the HKMA's principal day-to-day activity is the management of the Fund's assets.
除了确保外汇基金履行本身的法定职责外,金管局的日常工作,主要是积极管理外汇基金的资产.
Apart from ensuring that the fund meets its statutory roles,the HKMA's principal activity on a day-to-day basis is the active management of the fund's assets.
除了确保外汇基金履行法定职责外,金管局的日常工作主要是积极管理外汇基金的资产.
This fall within the company's range of activity.
这属于公司多种业务活动之一.
What were the principal conclusions of Hitchcock's survey?
希治阁的调查有什么主要的结论呢?

这家公司首要的活动领域是什么?