1. Mushrooms might be banned if they were judged by the same standards that apply to food additives. 【结构分析】句子主干为：Mushrooms might be banned；“if they were judged by the same standards that apply to food additives”为if引导的条件状语，其中“that apply to food additives”为that引导的从句来充当“the same standards”的后置定语。
2. He got no encouragement or assistance from others because they knew of many similar stories that had come to nothing. 【结构分析】句子主干为：He got no encouragement or assistance from others；“because they knew of many similar stories that had come to nothing”为because引导的原因状语，其中“that had come to nothing”为that引导的从句充当“many similar stories”的后置定语。
