合同管理的原则包括以下的 (42) 。
①事前预控原则 ②实时纠偏原则 ③充分协商原则
④公正处理原则 ⑤事后记录原则

A．①、②、③、④

B．②、③、④、⑤

C．②、④、⑤

D．①、②、③、⑤

The one-year spot rate is 6 percent and the one-year forward rates starting in one, two and three years respectively are 6.5 percent, 6.8 percent and 7 percent. What is the four-year spot rate（）

A. 6.51%.

B. 6.58%.

C. 6.57%.