YifanTIL that the expire date on your passport doesn't mean shit because traveling requires your passport to be valid for at least 6 month past departure or 3 months past expected return. They need to write this down on the passport because I cannot be the first person to fall for it.
Kevin Karhan 
@yifanlu that depends on the juristiction and visa requirements.
I.e. in many jursitictions your passport is allowed to expire the day you leave or even duringba longterm stay.
#NotLegalAdvice so check with the embassy of the destination countries!