The usual agreement is that playing the Queen promises the Jack (unless, of course it’s a singleton).
(a) Play ♠ Q and suggest to partner you’ve got ♠ J.
Had you played ♠ J instead of ♠ Q, partner will probably switch because you’ve denied ♠ Q
(b) Play ♥ 7. If you play ♥ Q partner may underlead from her remaining ♥ Kx
(c) Play ♦ 8 if you play high to encourage or ♦ 2 if low encourages. You are quite happy if partner chooses to play you for ♦ Q
(d) Play ♣ J. This card denies ♣ Q and warns partner of the danger of continuing the suit. You don’t want to give declarer an easy trick when holding ♣ Qxx.
Don’t play a lazy ♣ 10 or ♣ 9 because partner may not read the position correctly.