1, the topic forms are diverse: the topic forms of butterfly compulsory questions in junior high school include multiple-choice questions, fill-in-the-blank questions, analytical questions, etc. , covering a variety of questions, can comprehensively examine students' mathematical ability.

2, the difficulty of the topic is moderate: the difficulty of the topic to be brushed by Butterfly junior high school is moderate, neither too simple nor too difficult, and the students' mathematical level can be properly examined.