Shared Values And Normal Families

Let F be a family of meromorphic functions on a domain D, all of whose ze-ros have multiplicity k and poles have multiplicity at least 2, where k≥1 is an integer. for ev-ery f∈F,f=0(?)f(k)=1.If F1,F2(?)F,and for every f∈F1, there exists g∈F2 such that f(z) and g(z) share the value 0, F2 is normal, then F1 is normal on D.