An action that has happened at an unspecified time before now. It suggests that there is no need for repetition Can be placed before the main verb (past participle) or at the end of the sentence Examples:
What time does the film start? – It has already started.
What time does the film start? – It has started already.
Yet
Refer to events that have occurred up to now Examples:
He hasn’t arrived yet.
Have you eaten the apples yet?
For
Talk about a period or duration of time Doesn’t have to be an exact number, but it needs to refer to a period of time Examples:
He has lived in Paris for a long time.
We’re going to New York for the weekend.
Since
Refer to a specific point in time Examples:
I have lived here since 2010.
I have been walking since 5 p.m.
Ever/Never
Express the idea of an unidentified time before now Always placed before the main verb (past participle) Examples:
