TRICK 1.--As there are but six trumps in the two hands, Z
knows that one adversary must hold at least four trumps, and should
the force be taken and the trumps led, the adversaries would make
the entire suit of diamonds. Z must wait until Y is able to take the
ruff, in this way keeping his own trump strength intact.
TRICK 3.--A is placed in a difficult position.
TRICK 7.--With the best trump against him, Z must force the
commanding trump, for, no matter how the adversaries play, the spade
suit must be brought in.