4 sentences

1. 只有打下坚固的基础，才能在事业上取得成功。

   zhǐ​yǒu dǎ​xià jiān​gù de jī​chǔ, cái néng zài shì​yè shàng qǔ​dé chéng​gōng.

   Only by laying a solid foundation can one achieve success in their career.

   Source: Dong Chinese Dictionary

2. 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

3. 防空部队成功地打下了一架敌方的侦察机。

   fáng​kōng bù​duì chéng​gōng de dǎ​xià le yī jià dí​fāng de zhēn​chá​jī.

   The anti-aircraft units successfully shot down an enemy reconnaissance plane.

   Source: Dong Chinese Dictionary

4. 在猛烈的进攻下，我军只用了三天就打下了这座边境小城。

   zài měng​liè de jìn​gōng xià, wǒ jūn zhǐ yòng le sān tiān jiù dǎ​xià le zhè zuò biān​jìng xiǎo chéng.

   Under a fierce offensive, our army took only three days to capture this small border town.

   Source: Dong Chinese Dictionary