chứ không phải 
cannot, must not [ chứ ] : and, but (not); (finally particle) of course, sure, certainly
[ không ] : (1) no, not; (question tag); (2) air; (3) empty
[ phải ] : (1) correct, right (opposite of left), right (opposite of wrong); (2) must, have to
Most Common Compounds Set 1:
Most Common Compounds Set 2 :