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

<grammar>

air

air force

<i_f_v-sing>

37mm anti air artillery

37mm anti air machine gun

mixed air defense fcr

mixed air defense fire control radar

mixed anti air fcr

mixed anti air fire control radar

swa mixed air defense fcr

swa mixed air defense fire control radar

swa mixed anti air fcr

swa mixed anti air fire control radar

<i_f_v-pl>

37mm anti air artilleries

37mm anti air machine guns

mixed air defense fcrs

mixed air defense fire control radars

mixed anti air fcrs

mixed anti air fire control radars

swa mixed air defense fcrs

swa mixed air defense fire control radars

swa mixed anti air fcrs

swa mixed anti air fire control radars

<i_f_v>

37mm anti air artilleries

37mm anti air artillery

37mm anti air machine gun

37mm anti air machine guns

mixed air defense fcr

mixed air defense fcrs

mixed air defense fire control radar

mixed air defense fire control radars

mixed anti air fcr

mixed anti air fcrs

mixed anti air fire control radar

mixed anti air fire control radars

swa mixed air defense fcr

swa mixed air defense fcrs

swa mixed air defense fire control radar

swa mixed air defense fire control radars

swa mixed anti air fcr

swa mixed anti air fcrs

swa mixed anti air fire control radar

swa mixed anti air fire control radars