Although he had looked through all the reference material on the subject,he still found it hard to
问题描述：
Although he had looked through all the reference material on the subject,he still found it hard to
understand this point and her explanation only__to his confusion.
A extended B amounted C added D turned
请问答案和具体理由,
答
答案是C 题目的意思是尽管他查阅了所有相关资料, 但他还是很难理解, 而她的解释只增加了他的疑惑. 这里add to 是增加的意思 其他搭配都不行的
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