An uncountable noun cannot be made plural. See also Singular/ Plural Noun.
In example 1, “media” is already a plural noun, representing the plural form of medium. 
 
In example 2, the uncountable noun “research” appears in plural form. 
 

 

WRONG
RIGHT

1.

Today’s teenagers have grown up with medias and the internet.

Today’s teenagers have grown up with media and the internet.

2.

With the reference from the above researches, people believe that creativity in Hong Kong has been declining.

With the reference from the above research, people believe that creativity in Hong Kong has been declining.

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Click here for an exercise on countable/ uncountable nouns.

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