  Previous survey studies reported that coronal mass ejections (CMEs) can
exhibit various structures in white-light coronagraphs, and $\sim$30\% of them
have the typical three-part feature in the high corona (e.g., 2--6 $R_\odot$),
which has been taken as the prototypical structure of CMEs. It is widely
accepted that CMEs result from eruption of magnetic flux ropes (MFRs), and the
three-part structure can be understood easily by means of the MFR eruption. It
is interesting and significant to answer why only $\sim$30\% of CMEs have the
three-part feature in previous studies. Here we conduct a synthesis of the CME
structure in the field of view (FOV) of K-Coronagraph (1.05--3 $R_\odot$). In
total, 369 CMEs are observed from 2013 September to 2022 November. After
inspecting the CMEs one by one through joint observations of the AIA,
K-Coronagraph and LASCO/C2, we find 71 events according to the criteria: 1)
limb event; 2) normal CME, i.e., angular width $\geq$ 30$^{\circ}$; 3)
K-Coronagraph caught the early eruption stage. All (or more than 90\%
considering several ambiguous events) of the 71 CMEs exhibit the three-part
feature in the FOV of K-Coronagraph, while only 30--40\% have the feature in
the C2 FOV (2--6 $R_\odot$). For the first time, our studies show that
90--100\% and 30--40\% of normal CMEs possess the three-part structure in the
low and high corona, respectively, which demonstrates that many CMEs can lose
the three-part feature during their early evolutions, and strongly supports
that most (if not all) CMEs have the MFR structures.
