The rules that use the vocabulary item "a" are:

<hmmwv>

hmmwv with a tow

hmmwvs with a tow

<winged_aircraft_type-sing>

f and a eighteen

<i_f_v-sing>

brdm with a t

lar with a mortar

lav a t

lav with a mortar

<i_f_v-pl>

brdms with a t

lar with a mortars

lav a ts

lav with a mortars

<nlb-careful>

n a

<nlb-not_command_or_system_utterance_or_user_response>

n a

<airspace_nom>

c v o a four

c v o a one

c v o a two

<hmmwv-sing>

hmmwv with a tow

<nlb-nlb7>

n a

<winged_aircraft_type>

f and a eighteen

f and a eighteens

<nlb-not_careful-nlb7>

n a

<scale_number-gapsout_null-gapsin_null>

a thousand

a hundred thousand

<i_f_v>

brdm with a t

brdms with a t

lar with a mortar

lar with a mortars

lav a t

lav a ts

lav with a mortar

lav with a mortars

<winged_aircraft_type-pl>

f and a eighteens

<hmmwv-pl>

hmmwvs with a tow

<nlb-nlb8>

n a

<nlb-not_careful-nlb8>

n a