I am holding a second pr(mar2008-mar2013) and the first was(mar2003-mar2008) and I am out since nov. 2008. from Canada. Upto how much time i can stay out and must return back so that I don't loose my validity of P.R. please advise.STAYED THERE FOR 4 YEARS FROM JULY 2004 TO NOV 2008 CONTINUE SLY.