in act 1 when keller is talking to bert he says:"OH well ,there is no harm in oral " and "just whisper in my ear maybe i won't even hear it " explain how these sentences are an example of foreshadowing things revealed during act 2

The "oral" reading has to do with a thermometer. "Just whisper in my ear" has to do with the secrets we want to know and those we cannot tell. Bert can't say the word because its wrong, whereas Keller alludes to the fact that if it's a secret it isn't real.