John, together with some of American soldiers who ______ sent to Iraq ______ killed in a bomb explosion.
【正确答案】 C
【答案解析】分析句子结构可知，who引导的定语从句修饰some of American soldiers，所以谓语动词应用复数were。together with连接两个主语，主句的谓语动词应与前面主语的人称和数保持一致，即与John保持一致，所以应用单数形式。故选C。