Answer from cs61c-aq (Anjali Koppal 16454392) for Question 3
to delay the evaluation of an instruction, the hazard unit makes the instruction repeat one of its clock cycle processes again, eg: it might reread its values. 

repeating bubbles of this sort could lead to some problems if they are repeating many times. in the example i gave, if we reread the values for 3 or 4 cycles, we might end up with a different value for one of the operands, because, maybe the operand was written into by another instruction, during this time.