EW Vulnerable	North
West ♠  K 3 ♥  K 2 ♦  K 5 3 2 ♣  A K 10 8 5		East ♠  A Q J 10 4 2 ♥  A Q 7 3 ♦  A 7 ♣  4
	South
W N E S 1♣ - 1♠ - 2♦ - 4NT - 5♦ - ?
6♠ is of course a certainty, but perhaps there is more. No need for East to rebid his spades again. Instead East bids 4NT (Blackwood).   West shows holding one Ace. What should East do next ?