He was educated at the local high school, ______ he went on to Beijing University.

A．at which

B．after which

C．in which

D．during which

根据对商业银行内部评级法依赖程度的不同，内部评级法分为初级法和高级法两种。对于非零售暴露，两种评级法都必须估计的风险因素是违约概率。（）