S3. Studies at the Rocky Mountain Arsenal suggest that big, destructive earthquakes can be prevented by

A．Her unique experience.
B．Her future prospects.
C．Her favourite job.
D．Her lonely life.

A．It defined easy words as well as hard ones.
B．It was nothing more than a list of difficult words.
C．It included a number of everyday words.
D．It was considered to be a very valuable one.