7 sentences

1. 他低着头，仿佛在沉思。

   tā dī zhe tóu, fǎng fú zài chén​sī.

   He bowed his head as if in deep thought.

   Source: Dong Chinese Dictionary

2. 他低着头，陷入了沉思。

   tā dī zhe tóu, xiàn​rù le chén​sī.

   He lowered his head and fell into deep thought.

   Source: Dong Chinese Dictionary

3. 她紧锁着眉头，陷入了沉思。

   tā jǐn​suǒ zhe méi​tóu, xiàn​rù le chén​sī.

   She knitted her brows and fell into deep thought.

   Source: Dong Chinese Dictionary

4. 他屏去左右，开始独自沉思。

   tā bǐng qù zuǒ​yòu, kāi​shǐ dú​zì chén​sī.

   He dismissed those around him and began to contemplate alone.

   Source: Dong Chinese Dictionary

5. 听到这个消息，他陷入了沉思。

   tīng​dào zhè​gè xiāo​xi, tā xiàn​rù le chén​sī.

   Upon hearing the news, he fell into deep thought.

   Source: Dong Chinese Dictionary

6. 他合上手中的折子，陷入了沉思。

   tā hé​shàng shǒu zhōng de zhé​zi, xiàn​rù le chén​sī.

   He closed the folder in his hand and fell into deep thought.

   Source: Dong Chinese Dictionary

7. 他吸了一口冷气，发出嘶的一声，陷入了沉思。

   tā xī le yī kǒu lěng​qì, fā​chū sī de yī shēng, xiàn​rù le chén​sī.

   He gasped, made a hissing sound, and fell into deep thought.

   Source: Dong Chinese Dictionary