1 to demand

2 to request

3 to coerce

1 main

2 principal

3 major

4 primary

1 if only

2 so long as

1 to absorb

2 to assimilate

3 to ingest

4 to recruit

1 necessary

2 essential

3 indispensable

4 required

1 don't insist on only taking one road to Rome (idiom)

2 there's more than one way to skin a cat

1 incorporating diverse things (idiom)

2 eclectic

3 all-embracing

1 a blade will get rusty if it is not sharpened; a man will fall behind if he doesn't study (idiom)

1 to hit the target and do real damage (idiom)

2 fig. to hit where it hurts

3 fig. to hit home

4 an argument that hits the nail on the head

1 lit. you can't expect the horse to run fast but not let it graze (idiom)

2 fig. you can't have your cake and eat it, too