It might look for all the world like Black has nothing here; the lines to White’s king appear cluttered and inaccessible. The trick is to notice that White’s rook on a1 is loose, and then that Black’s queen is one move from being able to attack it with Qg7. (The open long diagonal should be conspicuous.) The question is whether the attack on the rook can be paired with a check to create a fork. A line from g7 to White’s king would need to be opened, so study the obstacles on that line—the little cluster of White bishop and Black pawn, with a White pawn on f5. This cries out for a pawn capture that clears both blockages out of the way: g6xf5—and now White has to either move the bishop or lose it. If he moves it, Black has Qg7+, winning the rook.

At first the g-file in this position looks hard to exploit constructively because of the two men that lie on it; Black’s pawn capture is a very useful maneuver, worth a good look, as it creates an unexpected open line in a hurry.

Notice that this position is structurally similar to the previous one. In each, you start by seeing that your queen is one move from being able to attack either the enemy king or a loose enemy piece (half a fork); and you see that the queen also would be aimed at the other half of the fork—whichever of those two pieces (the king or the loose piece) it wouldn’t be attacking directly. The hindrance in both positions was that one of the lines the queen needed was blocked; the challenge both times was to get rid of the blockader; the solution in each case was to start with a capture of something the blockader guards, forcing it to evacuate the needed line and leave it open.