If i arent wrong,u will need a merit to enter NTU or NUS.Of
course,there are exceptions.If you got lots of As and Bs and you
missed the mark for merit a little and get only a pass,chances are
u will still be able to get in.
this is correct. Anyway do NOT believe if you
need very good grades to get into NUS or NTU! 
me onli got A,C,C for As but managed to get into Mech. Engr. in
NUS! 
Now, ALWAYS apply and try out, no harm rite? and
when you get in, just get a bank, NUS will help you with this, like
DBS scholarship rental, they WILL
PAY for your school fees, and you ONLY
have to pay back like $500 per month AFTER you
graduate, INTEREST FREE, untill you FULLY paid
back. 
LIFE IS NOT AS DIFFICULT AS YOU THINK, JUST DO IT! 
you will come back and thank me, trust me! 