A．An ambitious and diligent person.
B． A reasonable and well-educated person.
C．An outgoing and being-around person.
D．A well-read and cultured person.
A．Because many things change quickly in the 21st century.
B． Because writers are out of date.
C．Because sometimes the date of publication is not accurate.
D．Because we need to make sure the contents are easy to find.