听力原文:To Americans, between 'black' and 'white' there are no other races. Someone with one black and one white parent looks black. Which of the following is NOT true about average Americans?
A.
They think there is a distinction between those purely white and the rest.
B.
They do not think there is much difference between black and brown races.
C.
They think black people include only those of purely African origin.
D.
They do not think it is good for a white person to marry a black one.