他对自己的信念始终坚定不移。

He remained ___faithful to his beliefs no matter what.

这本传记忠实地记录了这位科学家的生平事迹。

The biography offers a ___faithful account of the scientist's life.

这台打印机一直很可靠，从没出过故障。

This printer has been ___faithful for years without any issues.