Queen check: 3.Qa4+ Nc6 is variation 6 of 6 in the Queen's Gambit Accepted course, a intermediate opening course for Black (ECO D20). It runs 18 moves and begins 1. d4 d5 2. c4 dxc4 3. Qa4+ Nc6 4. Nf3 Nf6 …. White checks with the queen to win the c4 pawn back. Black blocks with the knight. Taking on c4 at once drops the d4 pawn, so White develops first. Black's knight then jumps to d5 and b6 and gains time on the queen. In the lesson every move is explained on a board and then drilled; it is free.
Move by move
1. d4 – White takes the centre.
1... d5 – Black claims the centre too.
2. c4 – White offers the c-pawn.
2... dxc4 – Black takes the pawn.
3. Qa4+ – White checks and attacks the c4 pawn at the same time.
3... Nc6 – The knight blocks the check and develops.
4. Nf3 – The best move. White protects d4 before taking on c4.
4... Nf6 – Black develops and keeps an eye on d5 and e4.
5. Nc3 – White develops and gets ready to take on c4.
5... Nd5 – The knight jumps to d5. It blocks the d-file and can go to b6 later.
6. Qxc4 – White wins the pawn back.
6... Nb6 – The knight attacks the queen and gains time.
7. Qd3 – The queen steps back and still protects d4.
7... e5 – Black hits the centre at once.
8. dxe5 – White takes on e5. Now the queens come off.
8... Qxd3 – Black trades queens.
The lesson goes on for 2 more moves, each with its explanation.
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