—— He looks so young! —— I agree with you. He looks 30, but he is __________ 45.

A．The Future of the Internet
B．The History of Computers
C．The History of the Internet
D．Convenient Internet Surfing

A．how rude a person can be
B．how one thing leads to another
C．where a person can’t tell the time
D．why you shouldn’t speak to strangers