Holding the ace, king, and jack of a suit, provided the queen is not
in dummy, it is often advisable to wait until your partner can lead
through the dealer’s hand. To lead through a king in dummy is sound
play, especially when you hold a sequence. Z cannot gain by covering
the honour led. He hopes that the ace will fall to the first or
second lead.
TRICK 5.--B indicates his suit before returning his partner’s original
lead.