问题补充：
Mail or gifts posted by companies to customers advertising.
A. are another
B. is the other
C. are other
D. is another
答案：
A. are another
B. is the other
C. are other
(答案→)D. is another
解析：本题考查主谓一致。句中由or连接的两个主语，其谓语动词与前一个主语保持一致，故谓语动词用单数；代词another指不定范围中的另外一个，故选D。
