4 sentences

1. 那老人喃喃地说他饿了。

   nà lǎo​rén nán​nán de shuō tā è le.

   The old man mumbled that he was hungry.

   Source: AI Challenger 2017

2. 他开始对自己喃喃自语。

   tā kāi​shǐ duì zì​jǐ nán​nán​zì​yǔ.

   He started mumbling to himself.

   Source: CCMatrix

3. 我喃喃地说了一个借口，然后离开了。

   wǒ nán​nán de shuō le yī​ge jiè kǒu, rán​hòu lí kāi le.

   I muttered an excuse and left.

   Source: CCMatrix

4. 我发现自己喃喃自语着祈祷，虽然我不太确定我在向谁祈祷。

   wǒ fā​xiàn zì​jǐ nán​nán​zì​yǔ zhe qí​dǎo, suī​rán wǒ bù tài què​dìng wǒ zài xiàng shéi qí​dǎo.

   I found myself muttering a prayer, though I wasn't quite sure who I was praying to.

   Source: CCMatrix