请教大家三道费费宝典，谢谢指导～

请教大家三道费费宝典，谢谢指导～

费费第六部分－第一题：in an insurance company,each policy has a paper record or an electric record, or both of them.60 percent of the policies having incorrect electric record and 75 percent of the policies having incorrect electric record have incorrect paper record.3 percent of all the policies have both incorrect electric records. If we randomly pick out one policy, what is the probability that it is one having both correct paper and correct electric record?答案：94%

我看了解答，但是答案是不是忽略了只有a correct paper record 和只有a correct electric record的情况，94％不止是both correct，还包括上述两种情况。

费费第六部分－第2题：

If for all x, x^2+ax+b=(x+c)^2,then a=?(1)b=0(2)c=3 答案：B

我觉得(1)b=0也可以吧，因为b＝0时c＝0；如果c＝0，则a＝0

费费第六部分－第15题：

过（0，-2）（-3，0）与哪条直线平行？

答案A：3y-2x=0

我觉得改选bd，3y+2x＝0或6

是不是答案打错了。

谢谢！

第一题，你对题目的理解是对的，但我认为a paper record or an electric record单独存在对答案没影响。

后两题跟你的观点一样。