  We propose a manifestly SO(8) invariant BF type Lagrangian for describing the
dynamics of M2-brane-anti-M2-brane system in flat spacetime. When one of the
scalars which satisfies a free-scalar equation takes a large expectation value,
the M2-brane-anti-M2-brane action reduces to the tachyon DBI action of
D2-brane-anti-D2-brane system in flat spacetime.
