We investigate the decays D0→π−ℓ+ν and D0→K−ℓ+ν,
where ℓ is e or μ, using approximately 7 fb−1 of data
collected with the CLEO III detector. We find R0​≡B(D0→π−e+ν)/B(D0→K−e+ν)=0.082±0.006±0.005. Fits to
the kinematic distributions of the data provide parameters describing the form
factor of each mode. Combining the form factor results and R0​ gives
∣f+π​(0)∣2∣Vcd​∣2/∣f+K​(0)∣2∣Vcs​∣2=0.038−0.007−0.003+0.006+0.005​.Comment: 5 pages, 2 figures, talk given at DPF'04, UC Riverside, C