We report on our determinations of B→πℓν, Bs→Kℓν and Bs→Dsℓν semileptonic form factors. In addition we discuss the determination of R-ratios testing lepton-flavor universality and suggest an improved ratio. Our calculations are based on the set of 2+1 flavor domain-wall Iwasaki gauge field configurations generated by the RBC/UKQCD collaboration with three lattice spacings of 1/a=1.78, 2.38, and 2.79GeV. We use the relativistic heavy quark action for b quarks and charm quarks are simulated with the Moebius domain-wall fermion action.