Englishfor English speakers
a
Determinative
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A is used when the following word could be any of a certain type.
Compare "A book I saw on the shelf" and "The book I gave you yesterday".
a
Noun
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A is the first letter of the alphabet.
The letter "a" comes before "b".
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In some schools, an A is a very high grade.
Ron got an A on his earth science test.
operator
Noun
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An operator is a person who operates something.
Jo is the operator of the tractor.
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An operator is a person who works on making connections for people over the telephone.
The operator was struggling to keep the line connected.