It was the first time ________ I ________ face to face with a thunder storm.

A．when / had come

B．that / have come

C．when / came

D．that / had come

下列关于贝塔系数的理解，错误的是()。

A．贝塔系数等于金融资产收益与市场组合收益之间的协方差除以市场组合收益的方差

B．市场组合的贝塔系数等于l

C．如果以各种金融资产的市场价值占市场组合总的市场价值的比重为权数，所有金融资产的贝塔系数的平均值等于l

D．贝塔系数是指金融资产收益与其平均收益的离差平方和的平均数