  New class of low- ionization BAL quasars (Becker et al. 1997), represented by
QSO 1556+3517, 0840+3633 and 0059-2735, is considered. Their optical spectra
are completely dominated by absorption features, whereas emission lines are
weak or absent. Possibility to explain these exclusive features of their
spectra by existence of molecular shells, responsible for the absorption is
discussed. In particular, it is suggested to identify line at lambda = 2063 A,
attributed to CrII, as a line of Cameron band of CO molecule. Estimation of the
expected optical depth value in rotational radio lines of this molecule is
made. It is suggested to carry out radio observations of quasars 1556+3517 and
0840+3633 to check the molecular hypotheses.
