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<正>Let (?) be a formation locally defined by f(p), G ∈(?) and A a ZG-module, where p ∈ $ = { all primes and symbol 88 }. Then a p-main-factor U/V of G is said to be (?)-central in G if G/CG(U/V) ∈f(p). In this paper, we have proved that: let (?) be