Americans sent a message to the world we have never been a collection of Red States and Bl

问题补充：

Americans sent a message to the world we have never been a collection of Red States and Blue States: we are, and always will be, the United States of America.

A. that, \

B. who, that

C. who, when

D. that, what

答案：

A. that, \

B. who, that

C. who, when

D. that, what

解析：本题考查定语从句及名词性从句。第一空先行词Americans，在定语从句中作主语，故用关系词who，第二空that引导同位语从句，解释说明名词message，故选B。