According to the author, the computer is an extension of our intellects. What, then, is used as an extension of our physical power

A．underestimate the strength
B．ignore the strength
C．rectify the strength
D．increase the strength

A．more and more students own mobile phones in China
B．it' s very convenient for students to communicate with each other by mobile
C．sending messages by mobile is becoming a hot new craze among students
D．students prefer mobile phones to the Internet