如何理解:Shortcomings of stress testing CCR include :(1)The linearization of delta sensitivities in models can lead to significant errors . 在计算压力情景下CCR的exposure的时候是怎么考虑的delta呢?是指计算期权衍生品的exposure的时候,用delta计算期权价值?(2)Using current exposure can lead to significant errors , especially for at - the - money exposures , when measuring derivatives market values . 是因为at - the - money时候gamma最大,最不准确么?