Derivation of the root formula of quadratic equation, determination of the positional relationship between two straight lines, derivation of infinitesimal quantity, etc. The correctness of mathematical operation, mathematical reasoning, mathematical proof, mathematical theory, etc. It can't be tested by repeated experiments like natural science, but can only be realized by strict logical methods. At this time, the big sister Shu Ting in the class stood on the steps, ready to blow out huge bubbles. She quickly turned over the bubble water with a straw and turned several times before stopping. Next, Shu Ting put the lid back on and shook the foam bottle vigorously. Her several processes really dazzled us all. I don't know which classmate shouted under the stage: "You want to tell us to wait until the Year of the Monkey." Shu Ting replied unhurriedly: "The eyes are wide open, and it's time to witness the miracle." In a flash, a huge bubble floated slowly in mid-air, and everyone "wow". I quickly blew a few small bubbles around it. Look, a few small bubbles and a big bubble are waltzing! Students also blew out a few small bubbles, and the sky suddenly filled with colorful bubbles. They may be accompanied by white clouds, the sun and the moon rising together ... The sudden ringing of the "ding" bell scared the bubbles to hide and suddenly disappeared. Let's blow dozens more bubbles, and there are more. All the students fell into Bubble Town, and the campus suddenly became the former residence of Bubble.