试题分析:先有
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823024116782268.png)
>0,
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823024116798255.png)
>0,可知a、b同号,c、d同号,由于此题从正面解答需分类讨论,此题作为选择题出现可利用取特殊值法对各小题进行逐一判断即可.
解:∵
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823024116782268.png)
>0,
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823024116798255.png)
>0,
∴a、b同号,c、d同号,
(1)假设a=1,b=2,c=﹣2,d=﹣1,则ad=﹣1>bc=﹣2,
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823024116782268.png)
=
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823024116845256.png)
<
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823024116798255.png)
=
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823024116876338.png)
=2,故此小题错误;
(2)假设a=3,b=2,c=5,d=4,则ad>bc,但是
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823024116782268.png)
>
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823024116798255.png)
,故此小题错误;
(3)假设a=1,b=2,c=﹣2,d=﹣5,则ad=﹣5<bc=﹣4,
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823024116923268.png)
=
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823024116938255.png)
>
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823024116954254.png)
=
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823024116969343.png)
,故此小题错误;
(4)假设a=1,b=2,c=2,d=1,则ad=1<bc=4,
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823024116923268.png)
=
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823024116938255.png)
<
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823024116954254.png)
=2,故此小题错误.
故答案为:0.
点评:本题考查的是不等式的基本性质,解答此题的关键是利用特殊值法,以简化计算.