整个句子为强调句，被强调成分为 lack of money, not of effort。由于句中插入 not of effort 这一结构，干扰了许多同学对 it was lack of money that defeated their plan 这一强调句的认识和理解。句子的意思是：他们的计划受挫，原因是缺少钱而不是没有尽力。所以选用that，希望我的回答对你有所帮助，呵呵！...
应该是：It was lack of money, not of effort, that defeated their plan.这是个强调句型。不能用作定语从句的。还原：Lack of money, not of effort, defeated their plan.是因为缺钱而不是缺乏努力才让他们的计划失败。...
