We simulate the transient absorption of attosecond pulses of infrared-laser-dressed atoms by considering a three-level system with the adiabatic approximation. The delay-dependent interference features are investigated from the perspective of the coh
erent interaction processes between the attosecond pulse and the quasi-harmonics. We find that many features of the interference fringes in the absorption spectra of the attosecond pulse can be attributed to the coherence phase difference. However, the modulation signals of laser-induced sidebands of the dark state is found related to the population dynamics of the dark state by the dressing field.
