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Using conjunctions such as when, while, before, after, until and since.
Time conjunctions introduce subordinate clauses that show when one event or situation occurs in relation to another.
Common time conjunctions include when, while, as, before, after, until, since, once, and as soon as.
When introduces a clause identifying the time at which an event or situation occurs.
For example, Call me when you arrive.
When is commonly used when one event occurs at or around the time of another event.
For example, When I opened the door, the dog ran outside.
When can also introduce repeated or habitual events.
For example, When I visit my parents, we usually have dinner together.
While introduces a time clause describing an action or situation that continues during another event.
For example, She listened while I was speaking.
While is especially common when the subordinate clause describes an ongoing activity.
For example, I fell asleep while I was watching television.
As can introduce a clause describing two events or situations occurring at roughly the same time.
For example, As I was leaving the office, my manager called me.
When, while, and as can all express simultaneous time, but while and as more strongly emphasize an ongoing or overlapping situation.
For example, When I arrived, she was cooking; While I was walking home, it started to rain; As I was leaving, he called.
Before introduces an event or situation that occurs earlier than the event in the main clause.
For example, Wash your hands before you eat.
Before can introduce a past event that occurred earlier than another past event.
For example, She had left before I arrived.
After introduces an event or situation that occurs later than the event in the subordinate clause.
For example, We went home after the meeting ended.
After can emphasize that one action was completed before the next action occurred.
For example, After she had finished the report, she sent it to her manager.
Until introduces the endpoint up to which an action or state continues.
For example, Wait here until I come back.
Till can function as an informal alternative to until in expressions of time.
For example, Stay here till I get back.
Until focuses on the endpoint of a continuing situation, while by the time focuses on a point by which another event has already occurred or will have occurred.
For example, I waited until six differs from By the time I arrived, the meeting had started.
Since introduces the point in time from which a situation has continued up to a reference time.
For example, I have lived here since I graduated.
Since clauses commonly occur with perfect tenses when the main-clause situation continues from a past starting point to the present or another reference time.
For example, She has worked here since she finished university.
Once introduces a time or condition meaning after a particular event has happened or a condition has been satisfied.
For example, Once the work is finished, we can leave.
As soon as introduces an event that occurs immediately or very shortly after another event.
For example, Call me as soon as you arrive.
When referring to the future, the time clause after as soon as normally uses a present form rather than will.
For example, I will call you as soon as I arrive, not as soon as I will arrive.
A subordinate time clause referring to the future normally uses a present tense rather than will.
For example, I will call you when I arrive, not when I will arrive.
A before-clause referring to the future normally uses a present form rather than will.
For example, Finish the work before you leave, not before you will leave.
An after-clause referring to the future normally uses a present form rather than will.
For example, I will call you after I arrive, not after I will arrive.
An until-clause referring to the future normally uses a present form rather than will.
For example, We will wait until she arrives, not until she will arrive.
Whenever introduces a repeated or indefinite time relationship meaning at any time when.
For example, Whenever I visit London, I use the underground.
Every time can introduce a repeated time relationship similar to whenever when an event occurs on each relevant occasion.
For example, Every time I see him, he tells the same story.
Expressions such as the first time and the last time can introduce clauses describing a particular occasion.
For example, The first time I visited Paris, I stayed near the river.
By the time introduces a reference point by which another event has already happened or will have happened.
For example, By the time we arrived, the film had started.
No sooner ... than describes two events occurring in very rapid succession and commonly uses inversion in formal English.
For example, No sooner had we arrived than it started to rain.
Hardly and scarcely can describe two events occurring almost immediately one after another, often with inversion in formal English.
For example, Hardly had I arrived when the meeting began.
A time clause can appear before or after the main clause, with a comma commonly used when the subordinate clause comes first.
For example, When I arrived, she left and She left when I arrived.
The tense chosen in a time clause depends on the temporal relationship and whether the reference is present, past, or future.
For example, When I arrived, she was sleeping; When I arrive tomorrow, she will be working.
Words such as before, after, and since can introduce either clauses or noun phrases depending on what follows them.
For example, before we leave contains a clause, while before lunch is followed by a noun phrase.
Some temporal expressions allow repeated material to be omitted when the meaning remains clear.
For example, When ready, let me know is an abbreviated version of When you are ready, let me know.
Use the time conjunction that matches the temporal relationship and use appropriate tense forms in future time clauses.
Common mistakes include using will after when or as soon as for ordinary future reference, confusing until with by the time, misusing since, and confusing while with when.