when

Pluralwhens

1. 1
   at the time thatconjunction

   At the time that something happens, every time it happens, or if it happens.

   Think of it like a trigger: the moment the first thing happens, the second follows.

   Put your pencil down when the timer goes off.

   The dog barks when someone knocks on the door.

   UsageFor the future, say when you get home (not incorrect: when you will get home).

   Similarwhenever, once, if

   Note
2. 2
   time asked aboutadverbinterrogative

   At what time, used to ask when something happens or will happen.

   When does the next bus leave for downtown?

   Do you know when the shop opens?

   UsageSay do you know when it opens? (not incorrect: when does it open).

   Note
3. 3
   adverbrelative

   The time at which something happens, as in 'the day when we met'.

   That was the year when we moved house.

   There are days when nothing goes right.

   UsageYou can also say the day we met, leaving out when.

   Note
4. 4
   conjunction

   And at that time, as in 'I stay till Friday, when I leave'.

   I'm here until Friday, when I fly to Rome.

   We were walking home when it began to rain.

   UsageSay I was walking home when it started to rain.

   Note
5. 5
   pronouninterrogative

   What time, used after a word like 'since' or 'till'.

   Since when have you liked spicy food?

   Till when are you staying?

   UsageSince when ...? can show you are annoyed.

   Note
6. 6
   conjunction

   Used to point out a contrast, meaning 'although' or 'whereas'.

   He keeps changing things when the old system works fine.

   You're picking at the scab when you should let it heal.

   UsageOften used with should: you're resting when you should be working.

   Similaralthough, whereas

   Note
7. 7
   conjunction

   Used to give a reason, meaning 'seeing that'.

   Why decorate, when I am the only one who will see it?

   Why are you still working when you are so tired?

   UsageOften after why: why walk when you can ride?

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