有如下 python 程序段:s = 1R2u3n_to45;num = 0for i in s: if a <= i <= z or A <= i <= Z: continue elif 0 <= i <= 9: num = num * 10 + int(i) else: break该程序段运行后,num的值为( ) A . 12345 B . 123 C . 45 D . 1 答案:B12.A.Making the bed.B.Folding the clothes.C.Doing homework.