1、 Priscilla Ouchuida's "energy-efficient" house turned out to be a horrible dream. …… a strange illness. (事例)
2、 Experts finally traced the cause of her illness.(直接原因)
3、 The Ouchidas are victims of indoor air pollution,….(深层原因)
4、 The problem appears it be more troublesome in newly constructed homes rather than old ones. (得出结论)