/,prəʊlɒŋ'geɪʃn; [US] -lɔ:ŋ-; ,prolɔŋ`ˇeʃən/ n
1 [U] prolonging or being prolonged 延长; 延伸.
2 [C] addition or extension that prolongs sth 增加或延长的部分.
the act of making something last longer
the prolongation of life
something added to another thing which makes it longer