Sequence of Tenses

WHEN + Past Simple, Past Simple

Usage: Expresses sequential actions in the past. \n Example: When he saw me, he smiled at me.

WHEN + Present Simple, Future Simple

Usage: Expresses sequential actions in the future. \n Example: When I see him, I will remind him to call you.

WHEN + Past Simple, Past Continuous

Usage: Expresses an action that was in progress when another action interrupted it in the past. \n Example: When I came to see her, she was cooking dinner.

WHEN + Present Simple, Future Continuous

Usage: Expresses an action that will be in progress when another action happens in the future. \n Example: When you come in, your boss will be waiting for you there.

WHEN + Past Simple, Past Perfect

Usage: Expresses an action completed before another action in the past. \n Example: When I arrived at the airport, the plane had taken off.

WHEN + Present Simple, Future Perfect

Usage: Expresses an action that will be completed before another action in the future. \n Example: When you return to the town, they will have finished building a new bridge.

AS SOON AS + Past Simple, Past Simple

Usage: Expresses consecutive actions occurring immediately one after another in the past. \n Example: As soon as she saw a mouse, she shouted and ran away.

AS SOON AS + Present Simple/Present Perfect, Future Simple

Usage: Expresses consecutive actions occurring immediately one after another in the future. \n Example: I will call you as soon as I have finished the work.

Present Perfect + SINCE + Past Simple

Usage: Expresses an action starting from a specific time in the past until now ("since"). \n Example: We have known each other since we were at high school.

BY + Past Time + Past Perfect

Usage: Expresses an action completed before a specific point in the past. \n Example: By last month, we had worked for the company for 9 years.

BY + Future Time + Future Perfect

Usage: Expresses an action that will be completed before a specific point in the future. \n Example: By next month, we will have worked for the company for 9 years.

AT THIS/THAT TIME + Past Time + Past Continuous

Usage: Expresses an action happening at an exact point of time in the past. \n Example: At this time last week, we were preparing for Tet.

AT THIS/THAT TIME + Future Time + Future Continuous

Usage: Expresses an action happening at an exact point of time in the future. \n Example: At this time next week, we will be having a big party in the garden.

BY THE TIME + Past Simple, Past Perfect

Usage: Expresses "by the time" an action happened in the past, another action had already been completed. \n Example: By the time she came home, everyone had gone to bed.

BY THE TIME + Present Simple, Future Perfect

Usage: Expresses "by the time" an action happens in the future, another action will have already been completed. \n Example: By the time she comes home, everyone will have gone to bed.

AFTER + Past Perfect, Past Simple

Usage: Expresses an action completed before another action occurred in the past. \n Example: After she had done her homework, she went out for a walk.

AFTER + Present Perfect/Present Simple, Present Simple

Usage: Expresses a routine action done right after completing another action. \n Example: After she has done her homework, she goes out for a walk.

BEFORE + Past Simple, Past Perfect

Usage: Expresses an action that occurred before another action took place in the past. \n Example: Before she went to bed, she had locked all the doors.

BEFORE + Present Simple, Future Perfect

Usage: Expresses an action that will be completed before another action takes place in the future. \n Example: Hurry up or the film will have ended before we go to the movie.

Future Simple / Imperative + UNTIL/TILL + Present Simple / Present Perfect

Usage: Expresses an action continuing "until" a point of time or another action occurs. \n Example: I will wait for you until it is possible. / Wait here until I come back.