I dreamed of telling a joke with my dead mother, and both of them laughed.

For the math test, everyone carefully reminded each other not to forget to bring their calculators. Only Datou confidently took out his new mobile phone to show off to everyone: "I only need to bring my mobile phone! Because my mobile phone has calculation functions."

The exam started, and everyone was pressing the calculator hard. Answer, except that Da Tou didn’t take out his mobile phone for a long time. After the exam, the students asked Da Tou with concern, and Da Tou said with a gloomy look on his face: "My mobile phone cannot be rooted!"