You are likely to pick on someone who is already attached or just not interested.

你可能会挑剔已经开始相处的恋人，或者对他失去兴趣。

Raise your hand, and the teacher will think you know the answer, so they'll pick on someone else. Reverse psychology.

举手，这样老师就会认为你知道答案，那他们就会叫其他人回答问题。这是逆向心理法。