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

<i_f_v-sing>

gainful fcr

gainful fire control radar

gainful launcher

gainful tel

swa gainful fcr

swa gainful fire control radar

swa gainful launcher

swa gainful tel

<i_f_v-pl>

gainful fcrs

gainful fire control radars

gainful launchers

gainful tels

swa gainful fcrs

swa gainful fire control radars

swa gainful launchers

swa gainful tels

<i_f_v>

gainful fcr

gainful fcrs

gainful fire control radar

gainful fire control radars

gainful launcher

gainful launchers

gainful tel

gainful tels

swa gainful fcr

swa gainful fcrs

swa gainful fire control radar

swa gainful fire control radars

swa gainful launcher

swa gainful launchers

swa gainful tel

swa gainful tels