[Harvard English] serve as

"When Bill Gates won a contract to provide an operating system for IBM; the resulting software served as the underpinnings of the Windows systems later sold on most PCs.

(Corpus 검색http://corpus.byu.edu/coca/)

# Mr. Sarkozy and Mr. Karzai cited changing circumstances in Afghanistan as the reason for NATO to change its calendar, but it may alsoserve as cover for the new French position. (NYTimes, 2012)

#We will identify a candidate to serve as U.S. ambassador to represent the United States government and our broader efforts to strengthen and deepen our ties with both the people and the government.(PBS Newshour, 2012)