C() Fo(O) ▲▲ FS 0O120,0 F(0δ(t) 0 t ( ) F0 ω 1 (1) 0 ω (t) δ T T1 t Fn 0 ω 0 ω F(ω) −ω1 ω1 1 2ω 1 − 2ω1 −ω1 ω1 2ω ω1 1 1 T FS FT