单项选择题 The top piston ring is plasma coated to give the lowest wear rate to reach the goal of two-years’ with sufficient margin（）

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（）