Atos 19:2

And he said unto them, Did ye receive the Holy Spirit when ye believed? And they said unto him, Nay, we did not so much as hear whether the Holy Spirit was given.

When ye believed ... This cannot mean, as suggested by Trenchard, that Paul expected that they had received the Spirit, merely upon their having believed;[2] but, as Plumptre said, the meaning is this:

Did ye receive the Holy Spirit when ye believed? that is, did you receive the Holy Spirit upon your conversion and baptism? We are left to conjecture what prompted the question.[3]

Plumptre is correct in seeing "believed" in this verse as a synecdoche for the whole process of conversion: faith, repentance and baptism.

Did not hear whether the Holy Spirit was given ... To be sure, as Boles said, "They had heard of the existence of the Holy Spirit, but not that he had been given on Pentecost."[4]

[2] E. H. Trenchard, A New Testament Commentary (Grand Rapids, Michigan: Zondervan Publishing House, 1969), p. 325.

[3] E. H. Plumptre, Ellicott's Commentary on the Holy Bible (Grand Rapids, Michigan: Zondervan Publishing House, 1959), p. 128.

[4] H. Leo Boles, Commentary on Acts (Nashville: The Gospel Advocate Company, 1953), p. 298.