Enough as an adverb
Adjective/adverb + enough
Enough is an adverb. It normally comes after the adjective or adverb it modifies.
She is old enough to be a grandmother. (NOT She is enough old to be a grandmother.)
It isn’t big enough. (NOT It isn’t enough big.)
You were not running fast enough.
I can’t wear your shoes – I haven’t got big enough feet.
Enough + noun
Enough can be used before a noun phrase as a determiner. Note that before a noun with a determiner (articles, possessives or demonstratives), we use enough of.
We have got enough rice.
I couldn’t answer enough of the questions.
Position with adjective + noun
We have seen that enough comes after the adjective it modifies. But when enough modifies an adjective and noun together, it comes before the adjective.
We haven’t got big enough nails. (We need bigger nails.)
We haven’t got enough big nails. (We need more big nails.)
Enough + infinitive
Enough can be followed by an infinitive.
She is old enough to know better.
These mangoes are ripe enough to eat.
I haven’t got enough money to buy an apartment.