Changing marquee

hi, ive been searching google for ages and I havent found it. I want to make a marquee that changes HelloWelcome to my siteclick here to visit my other siteand here to visit my forum

<marquee loop="infinite" bgcolor="white">
//first time it says
//next time it says
welcome to my site
//last time it says
this is hard

could i make it so on the first time it said “hello” on the second time it said “welcome to my site” and so on? thx in advance,yhack