adverb
1
BAD : People live longer in nowadays.
GOOD : People live longer nowadays.
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nowadays (WITHOUT in ): 'More women have executive jobs nowadays, especially in publishing.' 'Nowadays, computer skills are almost essential.'
2
BAD : This is a major problem for nowadays society.
GOOD : This is a major problem for today's society.
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Nowadays is an adverb (NOT an adjective): 'Video cameras are very popular nowadays.'