how to open pdf files

i have installed some pdf readers , such as kpdf ,xpdf ,but ,i ican't use them to read pdf files,,,
how to open the pdf files ?

都可以打开的啊。
可以安装acrobat reader，如果连那个都打不开就没办法了。

Some PDF files may be produced by very recent version of Acrobat. If these PDF file format is version 1.5+, you have high chance that kpdf, xpdf and even old version of Acrobat readers may not open it.

You may need a newer version of Acrobat reader. Linux version is available from Adobe's download site.

gpdf，ggv，都很不错，中文支持也是很好的，不过要求这些软件的版本是最新的。