все мы знаем, что существительные бывают исчисляемыми и неисчисляемыми.
но некоторые существительные могут быть одновременно
исчисляемыми и неисчисляемыми в своих разных значениях. одно из них - TIME.
в случае своей исчисляемости можно говорить a time.
If you say that something has been happening for a time, you mean that
it has been happening for a fairly long period of time.
He stayed for quite a time...
After a time they came to a pond.
You use time to refer to a period of time or a point in time, when you are describing what is happening then.
For example, if something happened at a particular time, that is when it happened.
If it happens at all times, it always happens.
We were in the same college, which was male-only at that time...
By this time he was thirty...
It was a time of terrible uncertainty...
Homes are more affordable than at any time in the past five years...
It seemed like a good time to tell her...
When you describe the time that you had on a particular occasion or during a particular part of your life,
you are describing the sort of experience that you had then.
Sarah and I had a great time while the kids were away...
She's had a really tough time the last year and a half...
You say at a time after an amount to say how many things or how much of something
is involved in one action, place, or group.
Beat in the eggs, one at a time...