2 sentences

1. 他说话支支吾吾，一定是心中有鬼。

   tā shuō​huà zhī​zhī​wú​wú, yī​dìng shì xīn​zhōng yǒu guǐ.

   He's hesitating and stammering; he must be hiding something.

   Source: Dong Chinese Dictionary

2. 他在回答时语带迟疑，显然心中有鬼。

   tā zài huí​dá shí yǔ dài chí​yí, xiǎn​rán xīn​zhōng yǒu guǐ.

   His tone was hesitant when he answered, clearly indicating he had something to hide.

   Source: Dong Chinese Dictionary