  From 2018 Oct 12 to 13, three successive solar eruptions (E1--E3) with
B-class flares and poor white light coronal mass ejections (CMEs) occurred from
the same active region NOAA AR 12724. Interestingly, the first two eruptions
are associated with Type II radio bursts but the third is not. Using the soft
X-ray flux data, radio dynamic spectra and dual perspective EUV intensity
images, we comparatively investigate the three events. Our results show that
their relevant flares are weak (B2.1, B7.9 and B2.3) and short-lived (13, 9 and
14 minutes). The main eruption directions of E1 and E2 are along
$\sim$45$^\circ$ north of their radial directions, while E3 primarily
propagated along the radial direction. In the EUV channels, the early speeds of
the first two CMEs have apparent speeds of $\sim$320 km s$^{-1}$ and $\sim$380
km s$^{-1}$, which could exceed their respective local Alfv$\acute{e}$n speeds
of $\sim$300 km s$^{-1}$ and $\sim$350 km s$^{-1}$. However, the CME in the
third eruption possesses a much lower speed of $\sim$160 km s$^{-1}$. These
results suggest that the observed Type II radio bursts in the eruptions E1 and
E2 are likely triggered by their associated CMEs and the direction of eruption
and the ambient plasma and magnetic environments may take an important place in
producing Type II radio burst or shock as well.
