“…Let X be a separable Banach space, (Ω, F, P, (θ t ) t∈R ) be a metric dynamical system. Consider a stochastic periodic semi-flow u : ∆ × Ω × X → X of period τ , which satisfies the semiflow relation u(t, r, ω) = u(t, s, ω) • u(s, r, ω), (1.1) and the periodic property u(t + τ, s + τ, ω) = u(t, s, θ τ ω), (1.2) for all r ≤ s ≤ t. SDEs and SPDEs with time-dependent coefficients which are periodic in time generate periodic semiflows satisfying (1.1) and (1.2) ([5]- [7]).…”