  QCD penguins are responsible for about 2/3 of the Delta I=1/2 rule in K to pi
pi decays, as inferred from a combined analysis of K to pi pi and KL to gamma
gamma. Further tests based on the decays KS to pi0 gamma gamma and K+ to pi+
gamma gamma are proposed. New insights into the treatment of pi0, eta, eta'
pole amplitudes are also reported.
