摘自《牛津高阶英汉双解词典》(第7版)1014页: if not---used to suggest that sth may be even larger, more important, etc. than was first stated (表示可能更大或更重要等)。 they cost thousands if not millions of pounds to build. 建设要耗费数千英镑,甚至可能是数百万英镑。 所以本句的意思是:最坏的部分是,很多甚至可能是所有这些错误都是可以避免的。本回答被提问者采纳