King, queen, &c.
Small card led.
Play queen.
In trumps it is sometimes right to pass, unless you hold ten also, or only three in suit.
Knave led.
The usual practice is to cover with the queen. But, it can be shown by calculation that, if the lead is from knave, ten, nine, and small, more is gained than lost, in the long run, by passing.
The best lead from knave, ten, nine, &c., is disputed; and so also is the question of covering.
King, knave, ten, &c.
Play the lowest of the knave, ten sequence.