4 sentences

1. 回首往事，他感慨万千。

   huí​shǒu wǎng​shì, tā gǎn​kǎi​wàn​qiān.

   Looking back on the past, he was filled with deep emotion.

   Source: Dong Chinese Dictionary

2. 我还以为你已经回首尔了。

   wǒ hái yǐ​wéi nǐ yǐ​jīng huí​shǒu ěr le.

   I thought you had gone back to Seoul.

   Source: OpenSubtitles

3. 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

4. 他走在路上，不时回首张望。

   tā zǒu zài lù​shang, bù​shí huí​shǒu zhāng​wàng.

   He walked along the road, looking back from time to time.

   Source: Dong Chinese Dictionary