讲义307页最后一段有个细节，请给解释下
1) 为什么说collateral不改变recovery value?collateral是credit risk 的mitigtor，处置掉collateral不是提高了recovery value么
2) 最后一句没看懂：Because of the linear increase in exposure brought by minimum transfer and threshold amounts, they would increase the CVA....这些措施不是降低CVA的么
