Consider verifiers in the usual sense:
Non adaptive : reads all positions of the proof predefined
Adaptive: Reads the proof iteratively.
Many lecture notes on PCP say the following: Adaptive verifier with q queries is equivalent to non-adaptive with some q' queries where q' is a constant and both using same randomness. In other words I think this means
Non adaptive q' queries can simulate adaptive q queries. But I don't see why? How to show this?