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UID570996在线时间 小时注册时间2010-10-4最后登录1970-1-1主题帖子性别保密 
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| Y has been believed to cause Z. A new report, noting that Y and Z are often observed to be preceded by X, suggests that X, not Y, may be the cause of Z.Which of the following further observations would best support the new report's suggestion? 
 
 
 (A) In cases where X occurs but Y does not, X is usually followed by Z.
 (B) In cases where X occurs, followed by Y, Y is usually followed by Z.
 (C) In cases where Y occurs but X does not, Y is usually followed by Z.
 (D) In cases where Y occurs but Z does not, Y is usually preceded by X.
 (E) In cases where Z occurs, it is usually preceded by X and Y.
 
 有人能告诉我怎么推吗?
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