Possible Duplicate:
What is the pronunciation of “the?”

I am not from the UK or the US, English is not my mother tongue.

I pronounce "the" as "the" (with e sounding like the letter sound) in the following example sentences:

  • Where is the apple?
  • That is the most extraordinary thing ever happened to my life.

My past English teacher has been correcting me saying that that pronunciation is incorrect before certain words. So when should I pronounce "the" as "the" and when as "thi"?