5 sentences

1. 他的这种乐观情绪有着坚实的心理依托。

   tā de zhè zhǒng lè​guān qíng​xù yǒu zhe jiān​shí de xīn​lǐ yī​tuō.

   His optimism has a solid psychological foundation.

   Source: Dong Chinese Dictionary

2. 这项研究为后来的科学发现奠定了坚实的基础。

   zhè xiàng yán​jiū wèi hòu​lái de kē​xué fā​xiàn diàn​dìng le jiān​shí de jī chǔ.

   This research laid a solid foundation for subsequent scientific discoveries.

   Source: Dong Chinese Dictionary

3. 通过努力，他为公司未来的发展打下了坚实的基础。

   tōng​guò nǔ​lì, tā wèi gōng​sī wèi​lái de fā​zhǎn dǎ​xià le jiān​shí de jī​chǔ.

   Through his efforts, he laid a solid foundation for the company's future development.

   Source: Dong Chinese Dictionary

4. 运动员们在坚实的土地上奔跑，留下一串清晰的脚印。

   yùn​dòng​yuán men zài jiān​shí de tǔ​dì shàng bēn​pǎo, liú​xià yī chuàn qīng​xī de jiǎo​yìn.

   The athletes ran across the solid ground, leaving behind a trail of clear footprints.

   Source: Dong Chinese Dictionary

5. 这种木材纹理细致，质地坚实。

   zhè zhǒng mù​cái wén​lǐ xì​zhì, zhì​dì jiān​shí.

   This wood has a fine grain and a solid texture.

   Source: Dong Chinese Dictionary