Englishfor English speakers
at
Preposition
—
Used to describe where something is, or when saying something's position
I am at home.
Let's meet at the pub!
—
The time at which something happened or will happen
Breakfast is at 9 o'clock.
At 5pm we went home.
—
Indicating something's state
At half price!
Water boils at high temperatures.
at
Symbol
—
The @ symbol, used to replace at
support@microsoft.com is an email address.
Apples @ £1.50 per kilogram.
least
Determiner
—
the smallest amount of; little of
She does the most cleaning, but the least cooking.
No German, least of all the East Germans, wanted Soviet troops to stay.
least
Adverb
—
Having the smallest amount of a characteristic in a group.
People are least likely to live in the far north.
The phone always rings just when you least expect it.
least
Adjective
—
The least is the smallest amount.
There are at least four problems with the idea.
The power is least in this case.
The least difference is still important.
Nobody works hard, but she does the least.
He was not the least bit interested my ideas.
This accident is the least of our problems.
one
Determinative
—
(ordinal first) The number 1.
We have one nose and one mouth.
one
Noun
—
The number 1.
One is the smallest whole number.
one
Pronoun
—
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.