In some languages like ______, pitch variations are meaning distinctive. Therefore they are called tone languages.

A．Optimistic.
B．Pessimistic.
C．Objective.
D．Not concerned.

A．To find ways to establish virtual education system and to provide education for all.
B．To examine the, changes in university in the past and in the future.
C．To promote the effort to solve problems of hunger, health through education.
D．To explore a new way to engage public efforts in writing books via internet.