2 sentences

1. 我开始纳闷，他们到哪里去了？

   wǒ kāi​shǐ nà​mèn, tā​men dào nǎ​lǐ qù le?

   I began to wonder, where did they go?

   Source: OpenSubtitles

2. 我心里正纳闷，他为什么没来参加会议。

   wǒ xīn​li zhèng nà​mèn, tā wèi​shén​me méi lái cān​jiā huì​yì.

   I was wondering why he didn't come to the meeting.

   Source: Dong Chinese Dictionary