How NOT to Win a STAC Game

Test your luck on this collection from the mid-May Sectional Tournaments at Clubs.  On each problem, you hold the hand displayed in the diagram.  My opponents' actions earned them a zero on each of these boards.  I am confident that you can do better.

North dealer, Both vulnerable:

What is your call?

North dealer, E-W vulnerable:

Doubtless you would have bid differently at your first turn; but now you have to go from here.  Your partner's raise was preemptive.  What's your pleasure?

East dealer, None vulnerable:

Again, you might have better facilitated the auction by starting with a 3♣ preempt; but what would you do now?

East dealer, None vulnerable:

North's negative double was ill-advised, as it risked losing a 5-3 fit; a 3♠ advance, or perhaps a cuebid of 4♦ (either 5-5 in the majors or a big club fit), would have been better.  In any case, the ♦K is led.  Plan the play.