im in grade 4 .piano.exam thsi august.i m now(half DEAD)i can sing.that;s my problem.i mean the major one.especally the C above midddle c.what should i do?my sounds will crack like toad if i over''strectched'' my voice.and that should sound quite embarassing .pleaseeeeeeeeeeeeeeeeeeee tell me.i don't want to make that irritable sound in front of the examiner.

Could you whistle instead? If the pitch is too high, you could sing it an octave lower.

The examiner doesn't care about the sound you make so long as he can tell what pitch it is at- and you will never meet him again (probably) so making nasty noises doesn't matter. You could also request, before the aurals start, that he doesn't ask you to sing above B or wherever you feel comfortable- so long as you don't also have problems singing a few notes below middle C.

???? Is this, like, in text message format?

Before my grades 6 and 8, I handed the examiner a sheet of paper with my singing range on and the pieces I was playing. This seemed to avoid any "over-stretching" of my voice in the aural,cause the examiner knew how high/low I could sing.

Just had a vision of a person going in and swearing at the examiner in perfect tune

not surprising, since one of my students' swear at everything he has to play. And yes, he sings in perfect pitch during aurals too