核心问题
Many principles of jet propulsion apply regardless of ____ air or water is the fluid used. A. what B. that C. whether D. either(TOEFL) 如何分析句中的 regardless of whether?
词典解答
可以把 regardless of whether 看作是复合从属连词,引导让步状语从句。类例: Regardless of whether or not he finds a job, he's getting married. 不管他是否找到工作,他也要结婚的。 (参见 adverbial of concession)