Melissa wrote a letter to President George Bush, Sr. for help but only received a form letter from the President twelve weeks later.

A、strcmp(str1, str2)==0
B、strncmp(str1, str2, strlen(str1))==0
C、str1 == str2
D、str1 = str2
E、strcmp(str1, str2)

A.参照物具有可比性
B．便于计算
C．排除参照物个别交易的偶然性
D．避免张冠李戴