Black board eraser: stress pattern

Well, you haven't shown it, but this is how I say it:

'BLACK board e RA ser (main phrase stress on the first syllable).

I wish I could upload that file.(I tried twice but fail to have it uploaded)

It says 'black board eraser' can have three different meanings depending on different stress it has.

First one is one that you did. My source explains that it means 'a eraser for black-board'.

Second one whose main stress is on board; this means 'an eraser for a board clored in black'.

Oh, that is just a pronunciation game, moon. I understand what the exercise wants to show you, but the 2 alternative phrases are only conjured up for the exercise; you will not meet them. Stress effects are easier to see with simpler examples:

She's a FILM director (not a play director).

She's a film DIRECTOR (not a film actor).

That's all the exercise is

Thank you.

Oh.. by the way the simple examples you drew don't seem simply for me

FILM director means a directo

They both mean the same thing. Stress tells us how they fit into the conversation.