oh, another one just occured to me.
Back in middle school, I was taught an expression "If I were you...". Using "were" instead of "was" is subjunctive mood. So I was taught.
But in real life, I've heard many Americans say:"If I was you..." (when the mood intended was obviously subjunctive)
And when I said "If I were you...." I got corrected by native speakers all the time. Now I almost tend to think my old grammar knowledge is outdated and the new rule is "If I was you..."
Would like to have a professional explanation on this. Thanks a lot.:)