Solution:
No article is required.

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Solution:
No article is used before abstract nouns. 'Unemployment' is an abstract noun.

Solution:
In the first blank, article "the" will be used because "USA" is a proper noun. In the second blank, article "the" will be used because "the" is used with superlatives. Similarly, In the third blank, article "the" will be used because 'world' is a proper noun.

Solution:
Specific ring that the first person gifted is being talked about and therefore 'the' article will be used.

Solution:
Here, the sentence talks about the 'player' as general class of things. Since we are referring to general things, we need to use the definite article 'a'.

Solution:
No article is required in the first blank because ignorance is an abstract noun while in the second blank, 'the' shall be used because the second part is about a specific person's ignorance.