What is the legal test for introducing an "unavailable witness" at the preliminary hearing?

Appellants' objections were overruled and the witness' testimony at the preliminary hearing was read to the jury. Appellants now contend that this procedure constituted reversible error. We do not agree. The instant case was tried after the effective date of Evidence Code, section 240 (January 1, 1967), which, together with the simultaneous amendment of Penal Code, section 686, changed the pre-existing law in California. (People v. Woods, 265 A.C.A. 803, 806, 71 Cal.Rptr. 583.) However, appellants at no time urged upon the trial court the proposition that the fact that the witness was absent from the state was no longer sufficient, without some further showing, to permit introduction of her earlier testimony as an 'unavailable witness.'