4 sentences

1. 大人有很多心事。

   dà​ren yǒu hěn​duō xīn​shì.

   Adults have a lot on their minds.

   Source: OpenSubtitles

2. 他最近心神不定，好像有什么心事。

   tā zuì​jìn xīn​shén bù​dìng, hǎo​xiàng yǒu shén​me xīn​shì.

   He has been restless lately, as if something is on his mind.

   Source: Dong Chinese Dictionary

3. 她好像有什么心事，总是闷闷不乐。

   tā hǎo​xiàng yǒu shén​me xīn​shì, zǒng​shì mèn​mèn​bù​lè.

   She seems to have something on her mind; she's always moody.

   Source: Dong Chinese Dictionary

4. 凭借多年的社会经验，他一眼就看透了对方的心事。

   píng​jiè duō nián de shè​huì jīng​yàn, tā yī yǎn jiù kàn​tòu le duì​fāng de xīn​shì.

   With his years of social experience, he saw right through the other person's thoughts at a glance.

   Source: Dong Chinese Dictionary