  A magnetic flux rope structure is believed to exist in most coronal mass
ejections (CMEs). However, it has been long debated whether the flux rope
exists before eruption or is formed during eruption via magnetic reconnection.
The controversy has been continuing because of our lack of routine measurements
of the magnetic field in the pre-eruption structure, such as solar filaments.
However, recently an indirect method was proposed to infer the magnetic field
configuration based on the sign of helicity and the bearing direction of the
filament barbs. In this paper, we apply this method to two erupting filament
events, one on 2014 September 2 and the other on 2011 March 7, and find that
the first filament is supported by a magnetic flux rope and the second filament
is supported by a sheared arcade, i.e., the first one is an inverse-polarity
filament and the second one is a normal-polarity filament. With the
identification of the magnetic configurations in these two filaments, we stress
that a flux rope is not a necessary condition for the pre-CME structure.
