Your 2♣ bid limits your hand to 12-17 points. If you had 18+ points you would need to rebid 3♣, jump shift.

You have maximum points (16-17) which means game could be on if partner has 8-9 points. Note that partner's 2♥ bid limits their hand to 6-9 points. They likely have just doubleton Heart, given they did not support your 2♥ bid in the 1st place.

So, bid 2♠. This bid shows maximum (with minimum you should pass the 2♥). It also shows 3 cards in Spades (with 4 cards you would have supported Spades before). This bid completes describing your 3-5-1-4 shape.

Now partner can bid game if they indeed have maximum: 4♠ if they have 5 cards in Spades, 3NT if they have 4 cards in Spades and a good Diamond holding, or 4♥ with the right cards. They can stop in part score with minimum.

Possible hands could be:

You can see that 4♠ is a great contract and easy to make.

Here, 3NT has a very good chance to make.

With this hand, 4♥ (and also 4♠) have a great chance to make.

It shows minimum hand, so need to remain in part score.

Note:

• Partner's 2♥ bid is just a correction and promises no more than a doubleton in Hearts.
• Your 2♣ bid can be passed if partner has 6-7 points and longer Clubs, seeing no chance for game. However partner may still bid 2♥ with a doubleton in Hearts and 3 cards in Clubs if they have 8-9 points, keeping the bidding alive for a possible game in case you have maximum (as per example 2 above).
• After your 2♣, the responder needs to have 6 cards in Spades in order to rebid 2♠ (or 5 really good cards in case of emergency). If they don’t they need to choose one of your suits.

Hand 3

Sitting West, against 4♠, you lead the ♣AK. All players follow with Clubs. What will you do next?

Sitting West, against 4♠, you lead the ♣AK. All players follow with Clubs. What will you do next?

You can count everything if you pay attention to the hands here.

You can count partner's points and distribution if you look carefully at the bidding. Declarer opens 1NT which is 15-17 points, so they have, let's say, 15 points. You have 11. Dummy has 13. So total is 39. That means partner has 0-1 point.

You can also count the distribution. When South rebids 2♥ after stayman (4 hearts, and maybe 4 spades), then North rebids 3NT (4 spades and fewer than 4 hearts), South chooses to stop in 4♠ (as they have 4 spades). So Declarer is showing 4-4 in the majors.

If Declarer has 4 cards in Hearts and 4 cards in Spades, it means that partner has a singleton Heart and doubleton Spade (you can work this out by looking at your own hand and the bidding for dummy).

Here you've 3 sure tricks in your hand; ♠A and ♣AK. So, you need 1 more to set the contract down.

In this case, playing your singleton Diamond, in the hope of getting a Diamond ruff, won't work, given partner only has 0-1 point. They'll never get the hand to let you ruff a Diamond. You'd only succeed if Declarer played a 2nd diamond, and there'd be no sense in them doing that before pulling out the trumps.

The setting trick has to come from a Heart ruff. You know partner has only 1 Heart from the bidding. So, play Heart at trick 3. When the Declarer wins and pulls trumps, you need to win it immediately with the ♠A (to protect partner's 2nd Spade) and continue with a 2nd Heart for partner to ruff.

Note:
a. Tips for defense:
- Count tricks
- Count partner's points, to know what to expect from them (it's almost always possible)
- Count partner's distribution according to opponent's bidding
- Think about the meaning of the lead (if partner leads)
- Think about where the setting trick is going to come from
- Think about timing (the right order to play your tricks).

b. When North bids Stayman and later 3NT, it's clear North has Spades as they don’t support Hearts. With no majors, North would’ve bid 3NT directly, without using Stayman.

c. Don't always lead a singleton.
- When you know partner is very weak, don’t lead singleton because you know partner won’t get the hand so you won’t be able to ruff.
- When you have AK, consider leading a Top card, and once you've seen dummy's hand you can then decide how to continue.
- If you have good cards in the trump suit, you might not want to ruff as you would win from a natural trick. For example here you have the Ace, but Ace of trumps will always win when Declarer plays trumps. Also, instead you may prefer to force Declarer to ruff from their long hand (by leading your long/strong suit), and try to take control of the hand.
- You can lead a singleton when you have weak trumps and/or when you know there's a chance that partner will get the hand to let you ruff.

Hand 4

Sitting South, you play 4♠.
West leads the ♥K.
East overtakes with the ♥A and continues with the ♦9.
You win with the ♦A. What will you do next?

Sitting South, you play 4♠.
West leads the ♥K.
East overtakes with the ♥A and continues with the ♦9.
You win with the ♦A. What will you do next?

Again, you can count everything here too.

From the bidding, we can see that opponents have 18 points and they should have at least 12 points in East and 6 in West.

Also, from the ♥K lead, it's clear that West holds the ♥KQ. As mentioned before, given East opened a bid, they should have at least 12 points, which means all the rest of the high honors (♥A, ♣K and ♠A) are in East's hands.

As cards opened, we have 3 losers (assuming Spades are not 4-0), 2 Hearts and 1 Spade. But here, East’s play, which is overtaking and switching to Diamonds, indicates that they have a singleton in Diamonds. Therefore a Diamond ruff by opponents will set the contract.

If you play Spades (or Hearts), East will take the ♠A, continue with Hearts to West's ♥Q and then a Diamond from West will let East ruff the setting trick.

To prevent this ruff, you need to "kill" their entries to West (prevent West getting the hand), by cutting communication between opponents. Therefore, play a Club to the ♣A and continue with the ♣Q, discarding a Heart when South covers with the ♣K. That loser on loser manoeuvre will keep East in hand and keep West away. Ruff the Heart return from East and play a Spade to the ♠J, losing to the ♠A. Then you can claim 10 tricks, losing 1 Spade, 1 Heart and 1 Club.