5 sentences

1. 他对那次失败一直耿耿于怀。

   tā duì nà cì shī​bài yī​zhí gěng​gěng​yú​huái.

   He has always brooded over that failure.

   Source: Dong Chinese Dictionary

2. 这位老大臣对皇帝忠心耿耿。

   zhè wèi lǎo dà​chén duì huáng​dì zhōng​xīn​gěng​gěng.

   The old minister was intensely loyal to the emperor.

   Source: Dong Chinese Dictionary

3. 我是对陛下忠心耿耿的仆人。

   wǒ shì duì bì​xià zhōng​xīn​gěng​gěng de pú​rén.

   I am a loyal servant to His Majesty.

   Source: OpenSubtitles

4. 他在公司工作了三十年，一直忠心耿耿。

   tā zài gōng​sī gōng​zuò le sān​shí nián, yī​zhí zhōng​xīn​gěng​gěng.

   He has worked for the company for thirty years and has always been devoted.

   Source: Dong Chinese Dictionary

5. 他一直忠心耿耿地辅翼着那位年轻的领袖。

   tā yī​zhí zhōng​xīn​gěng​gěng de fǔ​yì zhe nà​wèi nián​qīng de lǐng​xiù.

   He has been loyally assisting and supporting that young leader.

   Source: Dong Chinese Dictionary