单项选择题
A.save the time of connecting to the online system B.reduce the risk of losing information C.pay just local telephone charges D.get local information only
A.They can simply use a keyboard or a mouse. B.They should use a modem to maintain the host system. C.They should connect their computer to a satellite system. D.They can access its base through the programs on the system.
A.People usually feel depressed when their friends move away. B.People may call and write to their friends. C.People like their new friends very much if they get to know them. D.People must depend upon their friends for everything.