3 sentences

1. 回首往事，他心中充满了感慨。

   huí​shǒu wǎng​shì, tā xīn​zhōng chōng​mǎn le gǎn​kǎi.

   Looking back at the past, his heart was filled with emotion.

   Source: Dong Chinese Dictionary

2. 他不无感慨地叹道：“这真是奇迹啊！”

   tā bù wú gǎn​kǎi de tàn dào:“ zhè zhēn shì qí​jì a!”

   He sighed with emotion, 'This is truly a miracle!'

   Source: Dong Chinese Dictionary

3. 面对物是人非的景象，他不禁发出深深的感慨。

   miàn​duì wù​shì​rén​fēi de jǐng​xiàng, tā bù​jīn fā​chū shēn​shēn de gǎn​kǎi.

   Faced with a scene where things remained but people had changed, he couldn't help but sigh with deep emotion.

   Source: Dong Chinese Dictionary