After briefly ______the history of the author, Prof. Li turnes to the novel itself immediately.

A．It defined easy words as well as hard ones.
B．It was nothing more than a list of difficult words.
C．It presented good sentences to show how each word was actually used in speech and in writing.
D．It was the greatest improvement in the quality of dictionaries.

A．cut
B．shortage
C．lack
D．drain