单选题 ATM when referring to computers is a dedicated, connection switching technology that organizes digital data into 53-byte (69) units and transmits them over a physical (70) using digital signal technology. ATM is capable oftransniitfing at speeds of 155 or 622 MBit/s and faster.

【正确答案】 C
【答案解析】
【正确答案】 B
【答案解析】(69)～(70)[分析] cell意思为“单元，细胞”，cellunits在题目中意思为“信元”；medium意思为“介质，媒质”，它的复数形式为media或者mediums。本题主要介绍ATM技术传送的信元及其传输速率。