Solution of the Puzzles in D→K(K*)e+ve and Tansition Form Factors Among Heavy to Light and Heavy to Heavy to Mesons

We present a model-independent and systematic method for calculating the matrix elements among heavy to light and heavy to heavy hadrons. The new method allows us to obtain absolutely normalized form factors at the maximum momentum transfer for Q→Q' or q' induced weak transitions among meson states such as 0^-+→0^-+,1^--),0⁺⁺,1⁺⁺ etc. It is applied to the B-meson and D-meson systems and found that the puzzles in the D→K(K')_e+ve decays can be solved nicely.