His speech was riddled with holes, making it hard for the audience to follow his points.

riddled 是动词 riddle 的过去分词形式，riddle 本意是"使布满孔洞"，引申为"充满（问题或错误）"。 riddled with holes 字面意思是"布满孔洞"，在这里比喻"充满漏洞或缺陷"。