Yangdi Emperor of Sui, born Yang Guang had been living an extravagant life since his childhood. He knew nothing about the true life of the people. Ascending the throne, he abused the resources of the people and led the Sui court to the collapse. Tick the event that didn’t taken place during the reign of Yangdi Emperor:

A．An expedition against Korea in the east
B．The fight against the Tujue in the north
C．The inspection to Zhangye in the west
D．The building of the East Capital