单选题The speaker _____ several

问题补充：

单选题Thespeaker_____severalothersubjectsinthecourseofhistalkbutmostlykepthimselftothemaintopic.A.held onB.worked outC.touched onD.kept out of

答案：

C解析touch on简单谈到，由抠门的关键词：but mostly kept himself to the main topic.可知