The middlegame's first question is not "where can I make a three" but "which three is worth making". A shape near your other stones has follow-up: every later stone reinforces it. A shape on an isolated wing wins space nobody came to claim. Here black has a pair on the central row and a second pair far away in the corner — the corner pair also makes a three, but white sits right at its far end, so the "three" is capped before it is even born. Find the point that makes a genuine open three on the strong wing.
Solve the remaining tasks to finish this lesson.