請知道的XDJMs幫忙！謝謝！！ 謝！！

My daughter is a US green card holder. She was in this country from July 13, 2007 to August 03, 2007. She has been out of US since August 03, 2008. Her Form I-327 (Permit to Re-Enter) was issued on April 24, 2008 and will expire on April 24, 2010.

My question is: Does she have to enter US before August 03, 2009, which is two years after she left this country last time? Or she can re-enter this country before April 24, 2010, which is the expiration date of the Permit to Re-Enter.

Any information or advice will be greatly appreciated.