  We use the continuum random phase approximation to describe the muon capture
on C-12, O-16 and Ca-40. We reproduce the experimental total capture rates on
these nuclei to better than 10% using the free nucleon weak form factors and
two different residual interactions. However, the calculated rates for the same
residual interactions are significantly lower than the data if the in-medium
quenching of the axial-vector coupling constant is employed.
