句子的核心部分是migraine,afflicts perhaps 18 million americans E的错误在: 1.which 如果在此做定语从句的关系代词,其先行词就应该是前面的year,那么就改变了句子的意思. 2.which是如果做定语从句的关系代词,在从句中做主语,那么所指代先行词就是year--[sing],那么cost就要加S. 3.who collectively lose 64 million workdays year, which thus cost the nation $50 billion in lost medical expenses and work time. 改变句子的意思了.以which为关系代词,句子就是"工作年花费.." 4.还有一处改变句子意思. 正确选项:in medical expenses and lost work time. 此时的lost是形容词与medical平行.指的是浪费的工作时间. 原意就是"在医疗成本以及浪费的工作时间" E的意思"在浪费的医疗成本和时间".
一点看法.希望对你有用.
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