  We have tested complementarity for the ensemble-averaged spin states of
nuclei $^{13}$C in the molecule of $^{13}$CHCl$_{3}$ by the use of the spin
states of another nuclei $^{1}$H as the path marker. It turns out that the
wave-particle duality holds when one merely measures the probability density of
quantum states, and that the wave- and particle-like behavior is simultaneously
observed with the help of measuring populations and coherence in a single
nuclear magnetic resonance(NMR) experiment. Effects of path-marking schemes and
causes of the appearance and disappearance of the wave behavior are analysed.
