Tsumego (Capture) #5309479 (2-move)
Black to play — capture the marked white stones
Capture these stones
Why this move works
The answer is E2 then F1. The three white stones (G1, G2, F2) have liberties at F1 and E2.
Play E2 first. Filling F1 first lets White run out at E2. Stop the extension at E2, then fill F1 to capture.