Question: Where was the most precarious quake lake located?
Sentence: The most precarious of these quake-lakes was the one located in the extremely difficult terrain at Mount Tangjia in Beichuan County, Sichuan, accessible only by foot or air; an Mi-26T heavy lift helicopter belonging to the China Flying Dragon Special Aviation Company was used to bring heavy earthmoving tractors to the affected location.
Answer in sentence: yes