What is the passage mainly about

A．To study how students remember English vocabulary by short-term memory.
B．To study how students learn English vocabulary.
C．To study how to develop student’s ability in English.
D．To study how long information in short-term memory is kept.

A．Because future shock is caused by greatly accelerated rate of change.
B．Because future shock can not be predicated.
C．Because future shock prevent people from returning to a more familiar culture.
D．Because future shock can’t be explained in words.