Queen's Gambit Declined - Been-Koomen variation
1. d4 d5 2. c4 e6 3. Nc3 Nf6 4. Bg5 c5
White advances the queen's pawn to d4. Black moves the queen's pawn to d5. White moves the c-pawn to c4.
Black advances the king's pawn to e6. White develops the knight to c3. Black develops the knight to f6.
White develops the dark-squared bishop to g5. Black moves the c-pawn to c5.