Queen's Gambit Declined Slav accepted
1. d4 d5 2. c4 c6 3. Nf3 Nf6 4. Nc3 dxc4
White pushes the queen's pawn to d4. Black pushes the queen's pawn to d5. White plays the c-pawn to c4.
Black advances the c-pawn to c6. White develops the knight to f3. Black develops the knight to f6.
White transfers the knight to c3. Black captures on c4 with the queen's pawn.