Why do unfinished tasks keep popping into your head?
Unfinished tasks nag at your mind far more than finished ones.
Bluma Zeigarnik found that people remember interrupted or unfinished tasks better than tasks they have completed. The mind keeps an open loop on unresolved goals, pulling attention back to them until they are resolved.
A waiter recalls unpaid orders in detail, then forgets them the moment the bill is settled.
Your brain nags you about incomplete tasks - closure is what lets it let go.
Write down the open task to quiet the loop - on paper it stops hijacking your attention.
Open loops keep ringing.
Learn the idea and practice English at the same time.