You can take back moves with the cursor keys of your computer, and try different lines. The notation button below the diagram will show you the lines you have entered so far. However, White moves first, and there is no waiting move that retains the threat. Solution to ChessBase Puzzle Challenge 01You can enjoy video descriptions of the studies by FIDE Master Gauri Shankar, in his inimitable style. Puzzles in our replayer:Note that the first puzzle formed part of a famous study by the great Abram Gurvich.