1) feet, tomatoes, countries.
2) the best, small, coldest, heavier, fattest, better, the worst, more beautiful.
3) is, are, are, wasn't, is, was, Will Be, Was.
5) any, no, some, every, some, some.
6) begin - began - begun
eat - ate - eaten
study - studied
think - thought - thought
speak - spoke - spoken