WD mixing fractions in some representative classical novae determined by different elemental abundance ratios. Different marks represent the WD mixing degree from 10%−40%. The black stars refer to the observed data. The error bar represents the effect of the peak temperature on the elemental abundance ratios. Panel a: results of GQ Mus (Morisset & Pequignot 1996). Panel b: results of PW Vul (Andreä et al. 1994). Panel c: results of V842 Cen (Andreä et al. 1994). Panel d: results of V827 Her (Andreä et al. 1994). Panel e: results of V723 Cas (Iijima 2006). Panel f: Results of V2214 Oph (Andreä et al. 1994).