  The decays $D^0\to d\bar u\,e^+\nu\to a^-_0(980)\, e^+\nu\to\pi^-\eta\,
e^+\nu$ and $D^+\to d\bar d\,e^+\nu\to a^0_0(980)\, e^+\nu\to\pi^0\eta\,
e^+\nu$ (and the charge conjugated ones) is the direct probe of the two-quark
components in the $a^\pm_0(980)$ and $a^0_0(980)$ wave functions. Recent BESIII
experiment is the first step in experimental study of these decays. We present
a possible variant of $\eta\pi$ invariant mass distribution when $a_0(980)$ has
no $q\bar q$ component at all.
