which year are you in? year 3?
if it's year 3, you better dont go, really.... have this MP to
clear and other stuffs.
i'll advise you not to go. You can go Vietnam anytime, but common
tests cannot be postponed, right? Whatsmore the tests are more
important.
I actually thought of goin overseas too in june or july, and in
between i have to skip many impt classes and major project meetin,
luckily in the end i decided not to go.
You see, Skip lessons - take mcs, missed lesssons and impt meetin
couldnt be missed. Travel can be anytime. If it's because of the
money (flight ticket $) then give up on tests, i think it's rather
silly. I think im silly too last time but luckily i told my friends
i cannot go and i didnt book. Im actually the sibei 'on' kind that
is anything also can when it comes to playin, but this time round i
guess i've to be more sensible. 
Play can be anytime, but some things, once missed you cannot get
back liao.... 