Scientists learned about the barred owl migration by （）

A. a survey of farmers in northern Japan
B. tests performed on a thousand old people
C. the study of brain volumes of different people
D. the latest development of computer technology

A. When language is a barrier, people will find other forms of communication.
B. Everybody uses only one form of Communication.
C. Nonlinguistic language is invaluable to foreigners.
D. Although other forms, apart from language of communication exist, they are of little value.