单项选择题 Around the combustion chamber, all the main components are bore cooled to give low strains and the smallest, circumferentially symmetric deformations for good sealing between piston rings and liner（）

单项选择题 Around the combustion chamber, all the main components are to give low thermal strains and the smallest, circumferentially symmetric deformations for good sealing between piston rings and liner（）

单项选择题 Top piston rings are plasma coatedIt gives added safety for the of new lines（）