#11: White to move, is it a draw?
Solution #11: No, White wins because the h6-f8 diagonal is too short. Black couldn’t hold even his King reach rear position (h5).
#12: Black to move, can he hold?
Solution #12: Yes, 1…Bd7 and White could do nothing. Black will lose if 1…Bc4?? 2. Bg5 then White King can reach d6 by d4-c5.
#13: White to move, can he win?
Solution #13: No, Black Bishop controls both pawns from h2-b8 diagonal, and White King cannot break the blockade.
#14: Can White hold this position?
Solution #14: No, 2 Black Pawns are too far from each other. White Bishop is helpless in this position.
#15: Black to move, is it a draw?
Solution #15: Yes. 1…Kb2 (1…a2? loses) 2. Rb8 Kc1= (other moves will also lose)
#16: White to move, can he win?
Solution #16: Yes, using Opposition.
#17: White seems to be in trouble, can he hold?
Solution #17: Yes, again using Opposition. 1. d4!=
#18: White to move.
Solution #18: White wins. The only way to reach the key squares is through f2-g3-h4-h5, otherwise White King will face the Opposition.
#19: White to play, what should he do?
Solution #19: 1. Nf4=. He should find the right circuit: e2-c3-a2-c1. 1.Nf2?? will lose.
#20: White to move, what is the outcome?
Solution #20: Draw. 1. g7 h1/Q 2. g8/Q+ Kf1!= (2…Kf2? will lose after 3. Qa2+)