Bridge Tips – Playing, No. 1 - Solution

AQx

Play the Queen to draw declarer's King. If you play the Ace followed by the Queen, declarer will hold up his King until the third round and then you won't have a spade to lead to partner.

AJx

This is a bit trickier but the Jack is favourite. For them to get into 3NT, it's likely that declarer has the King or both King and Queen. If he has only the King, then, as above, he'll hold up if you play the Ace initially. If he has the King and Queen, there's nothing you can do to stop him winning both tricks if he has entries to dummy - but why tell him he has 2 certain tricks by playing the Ace! He may think you partner has the Ace and try something else that doesn't work for his extra tricks.

There is, of course, the risk that declarer has only the Queen, which he will make if you play the J, but that risk is low. However, if you feel their bidding may be based on only the Queen holding, then go up with the Ace and lead the Jack through to trap the Queen.