On shabbat for shacharit and mussaf, I am usually still davening shmoneh esre by the time the chazzan gets to kedusha. In this situation, can I hum to the tune of kedusha? This essentially boils down ...
Can you respond to קדושה if you are not already done with your own ש''ע? I heard that you can if you are past a certain point after שים שלום/שלום רב. I just want to know if that's true and, if so, ...