A DBL.—5 1 N.T.—3 2 N.T.—1
Your hand is too strong for one no trump but far too weak for a two-no-trump bid, which might be severely punished if opener's partner holds the balance of power. Doubling first, then bidding no trump at the lowest level indicates your 19 to 20 count.
B PASS—5 DBL.—2
Whoever plays the hand is apt to be in trouble, but if you double for penalty your partner is almost sure to be too weak to leave it in, and you, instead of your opponents, will land in the fire.
A 1 N.T.—5 2 [Diamond]—2 PASS—1
The no-trump response to a double shows 7 to 10 high-card points and a good stopper in the enemy suit. Two diamonds is a gross underbid. Your trumps are not strong enough to pass for penalties.
B 3 [Heart]—5 1 N.T.—2 2 [Heart]—1
Partner has asked you to bid the other major if you can, but you must jump to show that you have real values. One no trump at least has the virtue of announcing some high-card strength, which two hearts does not.
A 2 [Spade]—5 3 [Club]—3 1 [Spade]—1
Partner has asked for the other major, which you have in a good hand. Three clubs may work well since partner is likely to bid again, but if he does not you will have lost your best spot, the spade suit. One spade gets a point to distinguish its lack of merit from the infamy of two clubs.
B 3 [Club]—5 2 N.T.—3 1 N.T.—1
An immediate two-no-trump bid risks partner's insisting on a red-suit contract. Three clubs begins to picture your hand and, when followed by three no trump after partner bids in a red suit, will tell your story. Again, one no trump is better than two clubs.
A 2 [Heart]—5 2 [Spade]—2
An opening bid facing partner's double—the equivalent of an opening bid—should produce game, so the cue bid stands out. Partner might pass two spades.