The sentence particle 吧 ba, which we have seen used in surmise questions, may also occur in rhetorical questions when a more emphatic tone is adopted. It makes an enquiry which itself suggests the answer:
Tā shì lǎo shī ba ？
She is a teacher, isn’t she?
Tā bú shì lǎo shī ba ？
She isn’t a teacher, is she?
Tā men huì liū bīng ba ？
They know how to skate, don’t they?
Wǒ men bú shì míng tiān qù jiàn jīng lǐ ba ？
We aren’t going to see the manager tomorrow, are we?
 Yip, P. C., Rimmington, D., Xiaoming, Z., & Henson, R. (2009). Basic Chinese: a grammar and workbook. Taylor & Francis.