My previous postpost was getting edit and I think the edit was wrong.
Look at the Revision 2, sblair completely changed my post, which include a line here:
"I want one of my friends to buy a 1TB hard disk for me, but I have no idea about this value. I only know that 7200rpm is better (than 5400rpm)."
This is confusing because I know what does 1 TB stands for, what I am asking is the 2.5/3.5 value. So I think this edit is wrong, so I rollbacked it.
In some minutes slhck rollbacked my post to Revision 2, then I rollbacked it to the original one. Now I find out the original message is missing something which I typed(Maybe network reason). Sorry for that, and I edit it so that it is complete in Revision 6.
Than the moderator appear and rollbacked my post to Revision 2, abandoned all of my edit. I think it is unfair to abandon all of my change, all of my edit.