2 sentences

1. 我哪知道他今天不来？

   wǒ nǎ zhī​dào tā jīn​tiān bù lái?

   How was I supposed to know he wasn't coming today?

   Source: Dong Chinese Dictionary

2. 我哪知道你在说哪一天啊？

   wǒ nǎ zhī​dào nǐ zài shuō něi yī tiān a?

   How would I know which day you're referring to?

   Source: OpenSubtitles