Let F be a family of meromorphic functions on a plane domain D, let a,e be two finite complex numbers, and b, c, d be three nonzero finite complex numbers. If, for each f ∈ F, all the zeros of f - e are of multiplicity at least k ≥ 2, f(z) = a (→) f(k)(Z) = b, and f(k)(Z) = C (→) f (k+1)(Z) = d, then F is a normal family on D. The same result holds for k = 1 so long as b ≠ (n + 1)c, n = 1, 2 ….%设F是区域D内的一族亚纯函数,a,e是两个有穷复数,b,c,d是三个非零有穷复数,k≥2是一个正整数.若对于F中的任意函数f,f-e的零点重级至少为k,f(z)=a(<=>)f(k)(z)=b,f(k)(z)=c(=>)f(k+1)(z)=d,则F在D内正规.当k=1时,如果b≠(n+1)c,其中n为正整数,结论同样成立.
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