Active or passive by Matthias Huberschwiller

A: 2♦ - After declarer has drawn trumps, he will discard his losers on the Clubs.

You need to make an aggressive lead in Diamonds, where you have an honor, to try and set up tricks as quickly as possible.

Your result so far:

A: 2♠ - Each side-suit lead is dangerous and could blow a trick.

There is no reason to make an aggressive lead, since they have limited their hands, and have not shown any side-suits to discard their losers on.

A trump lead is the safest.

Your result so far:

A: 5♦ - With such a strong holding in the trump suit, you need to start a forcing defense. You need to force declarer to ruff in the long hand. This way you will gain trump control.

In order to do this, you need to lead your longest and strongest suit, Diamonds.

Your result so far:

A: 9♠ - Against 3NT, you should always try to make active leads, to set up your side's longest suit. How could you set up your Hearts? You would need a big miracle.

Let's think about the bidding sequence. They have not tried to find a major fit, so you know your partner has at least four Spades, and he's the one who will get back on lead. You need to lead a Spade for him. He'll thank you at the end of the deal.

Your result so far:

A: 2♥ - Opener has shown a weak hand. If there is strength in a suit, it will be in dummy. If you lead a Diamond and dummy shows up with the Ace-King-Queen, declarer will discard all his losers.

You need to lead aggressively, from a suit you have something in, but a Club would be too dangerous. It could set up dummy's suit.

You need to lead a small Heart: If your partner has something, it could set up tricks, and if he has nothing, the Ace-Queen will probably be in dummy, and declarer might choose not to finesse.

Your result so far: