关于纵隔肿瘤症状，下述哪项是错误的（）

A.其症状的程度及发生时间与肿瘤的部位，生长速度相关

B.大部分患者在体检时偶然发现

C.每一类肿瘤都有相应的症状

D.一部分患者有胸闷，胸痛症状

E.一部分患者有压迫相应器官的症状

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.

69（）

A．Router

B．Gateway

C．Bridge

D．Hub