学员疑问：The author would most likely argue that the reason an anteater does not dream is its brain is not complex enough to support the mechanisms that cause dreams. 老师，这个句子中reason后面的从句an anteater does not dream是不是省略的why。

老师解答：是的，reason后面接的定语从句引导词why常常省略，但是for which通常不省略。the reason for which (=why) an anteater does not dream

点评分析：不过，要注意，the reason 后面的定语从句，有时候引导词是that/which，根据先行词在从句中做主语（不可省略）还是宾语（可以省略）来确定是否可以省略。