H1B, job change question

Sorry, cannot type chinese here. I have a question, thanks.
my H1b will expire on 5/31/07. The attorney said that he would file for petition for next 3 years (my h1b is close to the end of 6yrs and my 140 has been approved with perm) after may 1. question is if i get the extension for 3 years, can i change job?

thanks.