Student or Learner
Ok, thats a great way :) Thanks.
As long as there is something else to go on, then they should be able to work out the overriding tense of the piece or at least the sentence that "read" appears in. 99% of the time, that will probably lead them to the correct pronunciation. I can't imagine a situation where it would happen, but the only time it would be impossible, both for learners and native speakers alike, to work out which pronunciation to use would be if "I/you/he/she/we/they read [+ noun] or [preposition + pronoun] etc" appeared as an absolutely standalone sentence with no surrounding clues.