Englishfor English speakers
a
Determinative
—
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".
—
In some schools, an A is a very high grade.
Ron got an A on his earth science test.
doppio
adjective
—
Having two shots of espresso.
doppio
noun
—
Two shots of espresso.