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.
short
Adjective
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If something is short then there is a small distance from the bottom to the top. The opposite is tall.
I can't reach the table because I'm too short.
The more I use the pencil, the shorter it becomes.
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If something is short then there is a small distance from the one end to the other. The opposite is long.
—
If something is short then it takes a little time.
one
Determinative
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(ordinal first) The number 1.
We have one nose and one mouth.
one
Noun
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The number 1.
One is the smallest whole number.
one
Pronoun
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One is a singular pronoun which means "someone" or "people". It is used more often in formal writing.
It is easy to see the difference if one looks closely enough.