stuck

Right. I need your help. I'm stuck on this darned quiz thing.

The whole thing is here if you want to play.

Alternatively, here are the three I can't work out....

7 Y in a S
12 T in an O
0 C B with A

(for the uninitiated amongst you, 24 H in a D would be 24 Hours in a Day)

Please put me out of my misery!

[update]2 down, 1 to go...

7 years in a septennial
12 tones in an octave (not ACTUALLY true but hey!)

so... what's 0 C B with A?[/update]