#21: White to move, can he win?
Solution #21: Yes, by cutting off the King with 1. Rh5! Please notice that 1. Rc1? will lead to a draw
#22: White to move, can he hold?
Solution #22: Yes. 1. Ke1 and White gets advantage in the opposition.
#23: White to move, can he win?
Solution #23: Yes. 1.h5+-. Otherwise, Black will play 1…h5 and his King can reach the key square f8 just in time.
#24: White to move, can White hold this position?
Solution #24: Yes, because Black King is outside of the winning zone. But White must be careful. The only correct move here is 1. Kf6=
#25: Black to move, is it a draw?
Solution #25: Yes. By using the “shoulder-charging”. 1…Kf3 2. Kb5 Ke3=
#26: White to move, what is the result?
Solution #26: It’s a draw. 1. Kd2 Kd6 2. Ke3=. Both sides wait to take the opposition.
#27: White seems to be in trouble, can he hold?
Solution #27: Yes, because he can get his Knight stand in front of Black Pawn. For central pawns (c, d, e, f-file), it is enough for a draw if we can manage to get the Knight stand in front of the pawn, even if it already reach 7th-rank.
#28: What is the correct move for White?
Solution #28: 1. Ne2 Kd2 2. Nd4 c1/Q 3. Nb3+ and he saves the game. Please notice that 1. Nd3?? is a big mistake and White would have nightmares for nights with this move. Because 1…Kd2 2. Nc5 Kc3 3. Ne4 Kd3 4. Nc5 Kc4, and there’s no more check.
#29: Looks pretty much the same with the problem #28. But can White hold?
Solution #29: Sadly no, because Black Pawn is close to the edge, White Knight does not have enough room to form a circuit. For example, 1. Nd2 Kc1 2. Nb3 Kd1-+, White wishes there were another column left to a-column for his Knight to jump but there’s no Genies in real life.
#30: White to move, what is the outcome?
Solution #30: It’s a draw. 1. Ng3 h2 2. Kb7. Now White Knight already made a barrier (e4, e3, e2, d2) so it takes time for Black King to approach and White King has enough time to support his brave warrior.