Q: How to extract rar zip files?

A: You can use 7zip to extract the rar zip files, it's free.And the following is the download link.
Free Compression Utilities : http://www.7-zip.org/



Q: How to View PDF files?

A: You need get adobe PDF reader to view PDF files, it's also free. And the following is the download link.
Free PDF Reader : http://www.foxitsoftware.com/Secure_PDF_Reader/


Q: After I download I try to open the zip file and it tells me that it is corrupt and invalid, why can't I download it?

A: ISPs are offering less reliable service these days, when download file, you'd better use firefox + DownThemAll Add-ons.And the following is the download link.
Mozilla Firefox Browser : http://www.mozilla.com/
DownThemAll add-ons : https://addons.mozilla.org/firefox/addon/201


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