  The co-presence of multiple Dirac bands in few-layer graphene leads to a rich
phase diagram in the quantum Hall regime. Using transport measurements, we map
the phase diagram of BN-encapsulated ABA-stacked trilayer graphene as a
function charge density n, magnetic field B and interlayer displacement field
D, and observe transitions among states with different spin, valley, orbital
and parity polarizations. Such rich pattern arises from crossings between
Landau levels from different subbands, which reflect the evolving symmetries
that are tunable in situ. At D=0, we observe fractional quantum Hall (FQH)
states at filling factors 2/3 and -11/3. Unlike those in bilayer graphene,
these FQH states are destabilized by a small interlayer potential that
hybridizes the different Dirac bands.
