18. Critics of sales seminars run by outside consultants point out that since 1987, revenues of vacuum cleaner companies whose employees attended consultant-led seminars were lower than revenues of vacuum cleaner companies whose employees did not attend such seminars. The critics charge that for vacuum cleaner companies, the sales seminars are ill conceived and a waste of money.
Which of the following, if true, is the most effective challenge to the critics of sales seminars?
(A) Those vacuum cleaner companies whose sales were highest prior to 1987 are the only companies that did not send employees to the seminars.
(B) Vacuum cleaner companies that have sent employees to sales seminars since 1987 experienced a greater drop in sales than they had prior to 1987.
(C) The cost of vacuum cleaner sales seminars run by outside consultants has risen dramatically since 1987.
(D) The poor design of vacuum cleaner sales seminars is not the only reason for their ineffectiveness.（A）
(E) Since 1987, sales of vacuum cleaners have risen twenty percent.
A为什么是削弱作用呢，哪为大牛帮助解释一下？
仔细查查以前的帖子，讲的很详细。
措施执行后的末态知道了。可是措施执行前的初态对比不知道
我刚才也做错了，看到weiyu NN的一句话，如梦初醒。其实我们做过很多类似的题目，象那种，两组小孩看电视，比较看完以后他们怎么怎么样，那种题目一看就知道，这种，换了个名目，穿了件马甲出来的题目，怎么就想不起来了呢？着急！
| 欢迎光临 ChaseDream (https://forum.chasedream.com/) | Powered by Discuz! X3.3 |