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We report measurements of the ratios branching fractions for B→D¯(*)πℓ+νℓ and B→D¯(*)π+π−ℓ+νℓ relative to B→D¯*ℓ+νℓ decays with ℓ=e, μ. These results are obtained from a data sample that contains 772×106BB¯ pairs collected near ϒ(4S) resonance Belle detector at KEKB asymmetric energy e+e− collider. Fully reconstructing both B mesons in event, we obtain B(B0→D¯0π−ℓ+νℓ)B(B0→D*−ℓ+νℓ)=(7.23±0.36±0.14)%, B(B+→D−π+ℓ+νℓ)B(B+→D¯*0ℓ+νℓ)=(6.78±0.24±0.18)%, B(B0→D¯*0π−ℓ+νℓ)B(B0→D*−ℓ+νℓ)=(11.10±0.48±0.23)%, B(B+→D*−π+ℓ+νℓ)B(B+→D¯*0ℓ+νℓ)=(9.50±0.33±0.34)%, B(B0→D−π+π−ℓ+νℓ)B(B0→D*−ℓ+νℓ)=(2.91±0.37±0.26)%, B(B+→D¯0π+π−ℓ+νℓ)B(B+→D¯*0ℓ+νℓ)=(3.10±0.26±0.22)%, B(B0→D*−π+π−ℓ+νℓ)B(B0→D*−ℓ+νℓ)=(0.99±0.43±0.20)%, B(B+→D¯*0π+π−ℓ+νℓ)B(B+→D¯*0ℓ+νℓ)=(1.25±0.27±0.15)%, where uncertainties statistical systematic, respectively. most precise these fraction date. The invariant mass spectra Dπ, D*π, Dππ systems studied, products B(B0→D2*−ℓ+νℓ)×B(D2*−→D¯0π−)=(0.157±0.015±0.005)%, B(B+→D¯0*0ℓ+νℓ)×B(D¯0*0→D−π+)=(0.054±0.022±0.005)%, B(B+→D¯2*0ℓ+νℓ)×B(D¯2*0→D−π+)=(0.163±0.011±0.008)%, B(B0→D1−ℓ+νℓ)×B(D1−→D¯*0π−)=(0.306±0.050±0.029)%, B(B0→D1′−ℓ+νℓ)×B(D1′−→D¯*0π−)=(0.206±0.068±0.025)%, B(B0→D2*−ℓ+νℓ)×B(D2*−→D¯*0π−)=(0.051±0.040±0.010)%, B(B+→D¯10ℓ+νℓ)×B(D¯10→D*−π+)=(0.249±0.023±0.015)%, B(B+→D¯1′0ℓ+νℓ)×B(D¯1′0→D*−π+)=(0.138±0.036±0.009)%, B(B+→D¯2*0ℓ+νℓ)×B(D¯2*0→D*−π+)=(0.137±0.026±0.009)%, B(B0→D1−ℓ+νℓ)×B(D1−→D−π+π−)=(0.102±0.013±0.009)%, B(B+→D¯10ℓ+νℓ)×B(D¯10→D¯0π+π−)=(0.105±0.011±0.009)%, extracted. This is first observation B→D¯1ℓ+νℓ D1→Dπ+π−.10 MoreReceived 8 December 2022Accepted 23 March 2023DOI:https://doi.org/10.1103/PhysRevD.107.092003Published by American Physical Society under terms Creative Commons Attribution 4.0 International license. Further distribution this work must maintain attribution author(s) published article’s title, journal citation, DOI. Funded SCOAP3.Published SocietyPhysics Subject Headings (PhySH)Research AreasBranching fractionLeptonic, semileptonic & radiative decaysParticles Fields