noun
1
BAD : We were surprised by their peculiar behaviours.
GOOD : We were surprised by their peculiar behaviour.
BAD : Such a behaviour can easily cause offence.
GOOD : Such behaviour can easily cause offence.
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Behaviour is an uncountable noun.
2
BAD : Sometimes Juan has a very strange behaviour.
GOOD : Sometimes Juan behaves very strangely.
GOOD : Sometimes Juan's behaviour is very strange.
BAD : There are very few people having such a behaviour.
GOOD : Very few people behave in such a way.
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Instead of using have + behaviour , use behaviour + be or use the verb behave + adverb: 'His behaviour is atrocious.' 'He behaves atrociously.'