TO BE- IN USE

They   will   be  doctors. (Noun)

They   will   be  through. (Preposition)

They   will   be  on holiday. (P.group)

They   will   be  exciting.(Ing group)

They   will   be  married.(Ed group)

They   will   be  to go on. (To group)

They   will   be  whom we need.(Sub clause)

They   will   be  happy. (Adj)

They   will   be  there. (Adv)

They   will   be  who to go. (WH- To group)

              They   will   be  whom. (WH