when

A good article will cover the who, the what, the when, the where, the why and the how.

When will they arrive?

Do you know when they arrived?

I don't know when they arrived.

When they arrived is unknown.

The site's all bugged. Fix when?

Tank class buff when?

My fridge even restocks itself these days. Glorious AI overlords when?

He's mister high and mighty now, but I remember him when.

That was the day when the Twin Towers fell.

Not a week goes by when I don't mourn that loss.

I recall when they were called the Greys.

Next year is when we elect a new mayor.

Love is when you can't get enough of someone.

Pavlov's dogs salivate when [i.e. at any and every time that] they hear a bell.

When [i.e. at any and every time that] he speaks to her, he is always polite.

Put your pencil down when [i.e. as soon as, at the moment that] the timer goes off.

A player wins when [as soon as, or at any time that, if] she has four cards of the same suit.

A student is disqualified when [as soon as, if] they cheat.

Don't forget to signal when (you are) turning right.

When she'd written her letters, she did some gardening.

Jose, when he finally managed to go to sleep, had a series of bad dreams.

They dream when [i.e. during the time that] they sleep.

I'm happiest when [during the time that, or at any time that] I’m working.

It was raining when I came yesterday.

The game is over when the referee says it is.

Be careful when crossing the street.

When (you are) angry, count to ten before speaking or acting.

I am here till Friday, when [i.e. at which time] I leave for Senegal.

I was just walking down the street, when [i.e. at which time] all of a sudden it started to rain.

I don't see the point of putting up Christmas decorations when I am the only person who is going to see them.

You're picking at your scabs when you should be letting them heal.

He keeps changing things when the existing system works perfectly well.

Since when do I need your permission?

Homer, to whom the Muses did carouse A great deep cup with heav'nly nectar fill'd, The greatest, deepest cup in Jove's great house, (For Jove himself had so expressly will'd) He drank off all, nor let one drop be spill'd; Since when, his brain that had before been dry, Became the well-spring of all poetry.