Adjectives used in one position only
We can use most adjectives in both positions - before a noun or after a linking verb. But a few adjectives can go in one position but not in the other.
Here are some examples of adjectives which can only go before a noun.
Be careful crossing the main road. The only problem is I've got no money.
Chess is an indoor game. The former footballer now trains young players.
Some more examples are: chief (= main), elder (= older), eldest (= oldest), inner, outdoor, outer, principal (= main), upper
Here are some examples of adjectives which can only go after a linking verb.
At last the baby is asleep. Emma's two brothers are very alike.
I'm really pleased to see you. Vicky looked ill, I thought.
Some more examples are: afraid, alone, ashamed, awake, alive, content (= happy), fine (= in good health), glad, unwell, well