SHORT STORY: INTELLIGENCE TEST

The teacher asked: "Who is the child of your parents, but not your biologSHORT STORY: INTELLIGENCE TEST
ical brother or sister?" Ti replied: "That's me, Ti." The teacher was very satisfied.
Teo's turn, the teacher also asked: "Who is your parents' child but not your biological brother or sister?". Teo scratched his head and ears: "Let me go home and think about it first."
When he got home and couldn't think of anything, Teo went to ask Teo: "Who is your parents' child but not your biological brother or sister?". Tet immediately replied: "That's Tei, who else?"
The next day, Teo happily came to class and showed off to the teacher, "I know who it is, it's Teo."
The teacher muttered: "Why is that, it has to be Ti, right?"