ing Yihang went first, and then a man in coach clothes and two cleaners walked in with their heads down.Ten minutes later Su Xilai looked for Ling Yihang and was called in by the people inside.there c...ally wrote a function limit problem and pushed it to Si Heng.Si Heng picked it up and looked at it twice, then began to solve the problem with a pen. In less than a minute, he wrote the calculation re...