Queen's Gambit Declined Slav defence - exchange variation

1. d4 d5 2. c4 c6 3. cxd5

白方出动后兵至d4。黑方推进后兵至d5。白方挺起c兵至c4。

黑方推进c兵至c6。白方用c兵在d5吃子。