In the late 1800‟s Ellen Richards, began work in the new field of “sanitary science” which was concerned with waste removal, water purification and ________.
句意： 在19世纪晚期， 艾伦·理查兹开始在“卫生科学”的新领域工作，这一领域涉及到垃圾的清除， 水的净化和通风。 此处用并列的名词形式。