某方案的建设投资为25000万元，流动资金为5000万元，铺底流动资金为1000万元，项目资本金为15000万元。其试运行阶段的年平均息税前利润和净利润分别为5000万元、3000万元，运营阶段的年平均息税前利润和净利润分别为6000万元、4500万元。则其总投资收益率（ROI）为（）。

A.13%

B.15%

C.20%

D.30%

For each blank, choose the best answer from the four choices and write down on the answer sheet.

(66) is a one-way function that takes an arbitrarily long piece of plaintext and from it computes a fixed-length bit string.

(67) is a protocol that most USENET machines now use it to allow news articles to propagate from one machine to another over a reliable connection.

(68) is an approach preferred by cable TV providers. In this solution the fiber terminates at an optoelectrical converter and the final segment is a shared coaxial cable.

(69) is a device used to connect two separate network that use different communication protocol.

(70) is a digital-to-digital polar encoding method in which the signal level is always either positive or negative.

66（）

A．MD

B．RSA

C．DES

D．MIB